here's a quick tip if you find you sometimes need a birthday card for a kids activity or whatever and aren't real fussy about cards.
don't hassle yourself with having to make a trip to the dollar store each time. instead when you are at the dollar store stock up and by 3,5, however many generic good enough birthday cards. so just keep a supply at home and use them when needed. when they get low or run out refill your home supply with several.
this may be totally standard. for some reason it took me a long time to realize how much easier it is to stock up on dollar store birthday cards. a couple of months ago there were some awesome cards at the dollar store. one was really weird and offbeat and just brilliant. another birthday card had an embedded deathwish in the cover art! they've since been used, I wish I'd taken pics to post here