5$ for a card advertising a shop is brazen in my opinion. I would have put back the card too. And bought another coffee instead. 
I sometimes buy postcards for 1,50€, but I don’t spend more. The only exception is when I find a special card for a friend’s collection, I think I spent about 3€ for such cards.
The most I would pay for a paper postcard in Japan and anywhere else is 170 yen (1,25 US dollars). I would pay a bit more for nice wooden cards.
The most expensive postcard I bought was 600 dinars in Serbia, Europe, which is around 5,25 US dollars, but I found it at an antique shop. The postcard was from about 100 years ago and I bought it for myself to keep.
The most expensive card I bought cost 4 €. In 2018 the City Theatre of Turku played “The Lord of the Rings” and during the interval they sold merchandice, including postcards of the production. But I can’t figure out why 4 € per card? Because of the price I bought only two and treasured them some time. Another I sent to a postcrosser friend and the other via postcrossing. I don’t know if she even realized what treasure she received.
After the last show I wondered what they would do with all the unsold merchandice and even considered emailing them and asking if they would like to sell the rest of the cards with discount to me. 
In general I rarely buy cards that cost more than 1,50 €.
My most expensive card must have been 5€ for a wooden card by a local artist.
I try finding cards cheaper than 1€ but in Belgium, this seems quite hard.
except our local tourist card. They are 0.50€ but i live in a small rural ‘city’/oversized town.
In big cities like antwerp or gent the average price is 1.25 and 5 cards for 5€.
Sets, postcard books and the internet are,for me, the cheapest solution.
The most expensive postcards I’ve bought have cost 2€. Nowadays, I have decided not to buy cards more expensive than 1€ unless it is a special case. Finding cheap cards is no longer easy.
Tourist cards in my city cost 0,40 - 1,00 Euro. The prizes for cards have increased rapidly last year and other cards cost 1,20 - 1,80 Euro now. In my favorite shop here the prize for each card is 1,50 Euro (or 11 cards for 15 Euro) now. I don’t like to buy online but I think I have to in the future.
I can understand not getting a postcard for a high amount. If there were a package of 5, I would get it. For me, I want to have enough variety for names I draw out.
I have paid $7.00 at Disneyland for postcards and I have actually spent 9.00 for a requested card that was out of print.
I’d pay no more than 1 euro/ 1.50 at a stretch.
I’ve bought some for 1.60 SGD or once even 2 SGD which is a little less than 1.50 euros.
I have seen cards at 3-4 SGD which seems way too much, I can have a meal for that price in some places and I’m not even joking.
I have bought them for 0,50 even in the North last month. The place with the really pretty ones had gone up to 0,80 (was 0,70 last time I went, over 1 year ago). I still saw some for 0,30. And this is an expensive tourist place in the North. I don’t think I can bring myself to pay one full euro… though as I said before I did in another currency
For cards I’m sending to others, the price varies a lot on the low end. Vintage cards purchased in lots can be very inexpensive, and I know of thrift shops where I’ve found amazing modern ones for (Canadian) 15 cents each.
I also buy a lot of tourist cards, which are in the 30-50 cent range, as are cards that I get printed through Zazzle.
But I’ll also buy more expensive cards ($1-2 each) if the artwork is great and/or I know of a specific recipient for them.
Cards priced above $3 are a very rare purchase for me because international stamps themselves are close to $3 each; that’s why I’m looking for ways to economize to begin with! More expensive cards than that are either gifts to friends or personal splurges to keep.
$5!!! Are you kidding!? I used to love sending postcards to friends or people in the office when I was away. Shops would sell postcards at 30pence each or 4 for £1. Not sure what cards cost now but $5 for a mass produced piece of paper is total nonsence! Such a shame as it will put people off sending cards.
I bought one for E2.30 this week because I thought someone I regularly exchange with would appreciate it but the rest have been 40c to E1 (temporarily in Spain) and I splash out a bit on holiday.
I try to look at it on averages - boxed sets / bundles maybe as little as 10p or even less so overall its ok
For an actual postcard meant to be sent I wouldn’t pay more than 25 kr (2,18 euro) piece and that would be a bit high for Postcrossing card in my opinion so I would be very carefully about selecting who I send it to.
I think there might be some confusion about mixing up art prints with postcards. I would gladly pay more for postcard sizes art print, but I wouldn’t send that one as a postcard (have sent some as a gift and then they were wrapped carefully and had cardboard support). I have seen some artist selling their postcard sizes art print as postcard when they should just call them art prints instead. I have paid up to 100 kr (8,70 euro) for art prints of that sizes. With pretty frames they make very nice decorations on walls.
Yeah, I would have assumed they are free too, like it is just a logo on postcard? Surely it is an ad card. Wouldn’t have paid that much no matter how fancy company it is
If they would have worked with local artists to create their own company themed postcards with bit more twist than just a logo, I would have maybe bought one as a keep-sake… If I liked the coffee.
The most I’ve ever paid was for a set of 6 postcards, illustrated by a local artist. That was £6, and I thought ‘what a good deal, £1 per postcard by a really good local artist!’
Generally, about $1/card is my limit. Exceptions have been when it’s an especially nice card, or I am directly supporting an artist. Then I might be willing to go to $2/card as an absolute maximum for a postcard I am going to send in the mail (I would, however pay more for a postcard-sized art print I plan to keep).
I also buy box sets and postcard books that work out to be significantly less per card so that helps balance out the cost.
I try to keep it under $2/postcard. Preferably $1 or less. It’s difficult to find much cheaper than $1. Most so far have been for sale for $1.50 and up. A lot are asking even $8!!
I found them to be reasonable in museum gift shops, but so far not much to choose from.
I went to my State Park yesterday and she said they are phasing them out and won’t be selling any more.
Normally, I buy my postcards by the bulk online. I bought an exquisite set of New Yorker cards: 100 cards for $27.00. Normally, I buy a box of 100 cards for about $20.00. Next week I’m going to Buffalo, NY, for a wedding and I will want to buy cards while I’m there (of Niagara Falls, etc.). I’ll probably pay whatever they’re charging since I’m not going to pass that way again anytime soon. Normally, I think postcards are cheaper by the bulk; individually, I think you’ll end up paying more.
The most I would pay would be $2, but it would have to be a really great card, and probably one I wanted to send to a specific person I knew, rather than on official PC.
Most of my cards cost between 10 cents (for a bulk order of mixed cards) and 60 cents.
$5 for a coffee shop ad card? No wonder there was a big pile left 
And I don’t think there’s anything remotely rude about putting something back once you learn the price. If anything, it’s manipulative on the part of an establishment to not display the price, especially when it’s so outrageous. They probably know that the only way any are going to sell are to people who are too shy to put it back after asking. Good for you for not falling for that trick!
I wonder, though, are people buying them? Like @cliffside said, when he originally sold cards at .99 people didn’t purchase so he dropped to .49. If people weren’t buying them at $5, wouldn’t the shop drop the price? I’m not sure how long they’ve been selling them, but I wonder if some unknowing (or particularly high spending) people are actually paying $5.
For me max. 2€, but if they were extremely beautiful I would pay max. 1€ more.