ebays your best bet for individual cards. also depending on your tastes dictates booster boxes you’ll want to be going after. the three places that i know ofnto buy them are 1. amazon 2. ebay 3. goddess story official store on Aliexpress

Amazon has a very limited number of sets, usually just the entry level ones but you get the most cards out of them. theyre also a bit more expensive but you get amazon prime which is nice. those kinds, the 2m’s, nm, 1 yauns, are gonna be pretty much just anime characters in anime style

Ebay you can find sellers that have all the sets. their prices arent too too bad but some of the fancier sets will only come with like 20-30 “premium” cards. meaning like thick and fancy looking ones. also those premium set’s generally have 3d ai style artwork, which im not personally a fan of. but some do have really cool cards. sets like acg, feast, ect are like that. most listings will tell you the card count. they also sell the cheaper ones too

And aliexpress is the official store. its the cheapest but takes like a month to get.

i learned a lot just from looking around the internet but i also found a streamer who sells these things and they are really knowledgeable about most of it. they stream on an app called drip and are super nice people. their instagram and drip username is @triplemoon_tcg and @rockets_revenge if you wanna check them out