there are some print-on-demand card and game manufacturers that might be less expensive than you think. I’m a hobbyist game designer and I’ve used thegamecrafter.comthegamecrafter.com as well as makeplayingcards.com to have custom cards printed, and it wasn’t particularly costly.
but if those services do charge more than you want to spend, the thing I recommend most strongly is that whatever stock you decide to print on, cut them with one of those sliding-blade paper cutters. don’t try to cut them with scissors. they’ll come out a lot more even.