1 inch unfinished wood rounds are absolutely dirt cheap. You don’t have to cut them to shape and they’re sturdier than foam board too.
Maybe a hardware store, or any sort of craft store. They are on Amazon too, but it’s for a pack of 50. There is even a comment about DnD in the reviews. lol
https://www.amazon.com/dp/B01CSV14JE/ref=cm_sw_r_cp_api_m5HKBbGA9YAEM
Get some wooden disc's from Amazon or a craft store.
https://www.amazon.com/dp/B01CSV14JE/ref=cm_sw_r_cp_apa_i_p-XVDbR27GSP7
Also get a circle punch of the same size: https://www.amazon.com/dp/B013NESBKK/ref=cm_sw_r_cp_apa_i_vaYVDbEGWXAV3
You can either print out artwork on cardstock or even use common pokemon cards to punch out the art.
Take a tiny bit of Elmer's glue, wood glue or some sticky tack, and glue the art to the wooden discs. Boom. High-quality tokens.
This is a trick used in the Roleplaying community to make tokens for their characters and NPCs without breaking the bank. ~15 dollar investment gets you like 100 tokens.
I reccomend between 1 inch and 1 1/2 inch for the size. Depends on your purposes.
Have fun!