Not that I need any more postcards anytime soon… 
But I’m curious what is your cue to buy more? Do you keep a certain number on stock and order when you’re under that amount? Order whenever you come across a deal? Or just buy cards whenever you feel like it?
Before I crossed the 300 card threshold, my criteria were to not buy any new cards until I had less than 200 in stock. Now that I have over 700 in stock, I need to re-evaluate my criteria.
I like unusual and weird postcards which aren’t always easy to find. But as soon as I do find a shop that sells those cards… sigh… I’m afraid there’s no turning back.
Ah, you just change the meaning of “too many” into “not enough”.
I just buy cards if I feel like it - an that is not very often.
I don’t know if you ever buy on Amazon, but I just got the Accoutrements Super Awesome Postcard Book and there are some unusual and weird postcards in it. I recommend checking it out.
You see? This is another way for getting a nudge to buy more postcards. 
I buy postcards whenever I see a deal–because I know there will be certain times of the year when I will be sending out hundreds of postcards (not just Postcrossing related). For example, some time last year, I heard that the warehouse for Chronicle Books–which is a publisher for a lot of postcard sets–was having a sale. I went there and managed to score several postcard box sets for ~$5 each because they were trying to get rid of overstock.
It is so hard to find postcards here so I just buy any I happen to find. I have quite good variety and number of cards now, but it is really slowly collected one card from there and couple from here… Honestly it is a wonder I still have so many left even though I haven’t been able to go buy cards for months now. Starting to think the cards are reproducing by themselves 
I… buy postcards way too often, and I stock up on them more than they are actually sent out. 
I typically buy postcards when:
Not that I need more postcards anytime soon, but… You can never have too many, right? 
This whole thread is for enablers! I love it!
My cue to buy more postcards is when I am starting to struggle to find the right card for an official profile that I have drawn. I have 3 tins/boxes of postcards, and while I don’t count the cards I have at any one time, once they aren’t full to the brim I think it’s time for me to get new ones. I try not to go beyond that amount though. For the tourist postcards I like to keep about 20 on hand at least, usually reserved for those new members who haven’t ever received a card from Hong Kong before. As they’re coming up quite a lot these days, I think it’s time to stock up!
[Enabling commences]
I immediately thought of these little guys. They might be the weirdest set I’ve found. 
These are hilarious!
Omg i just look at those cards! i was about to buy it but the shipping cost to my country is almost 30 dollars… i’m like nvm
… seeing more postcards?
I don’t even want to know how many cards I have… When ever I see postcards sold somewhere, I go to see if there is anything suitable for postcrossing. I always stock up on most popular themes. It is easier when I have enough cards at home to choose from, rather than hunt for them whenever needed. Last spring I had a bit of troubles finding local touristic cards for the summer. Shops were either closed completely or open for limited hours and they mostly had just winter images.
No self-control here. I buy cards when I see some and think “Postcrossers are gonna love these”, which is the case very often! Or when I’m low on tourist cards. Or when I’m not low on tourist cards but I’m at a city I don’t get to often, like Cologne some weeks ago. Or when I’m browsing Etsy and locally made and discounted packs of cards show up… 
i buy most of my cards online. there are a few shops with postcards here, but not enough to buy a lot of different cards. well and i haven’t been all year because of covid, i basically just go to the supermarket.
so i buy my cards online. that mostly happen when i check my favourite webshops to see if they have new cards. and then i’m like well let’s put some in my basket and see how far i’ll get. and then next you know it i’ve placed an order.
that happened already 3 times the last few months. and now i discovered a new webshop through the forum and my hands are itching but i reaaaally don’t need cards anymore.
and i have this rule with myself that i don’t buy more cards than can fit in the basket i keep them in, and i’m kinda at my limit now.
I love these so much 
Maybe you just need a bigger basket.