i bought mine off amazon. I use 10 gallon for tomatoes, peppers don't need to be that big (5 gal is probably fine). Don't bother with the ones with the flap underneath, it's pretty useless.

I bought these last year and they've served me well. I also have some with the potato flap but I never use the flap.

https://www.amazon.com/gp/product/B08FC896PH/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

I prefer the felt bags rather than the plasticky ones. Anything on amazon with decent ratings is probably a safe bet, I've gotten a few kinds and they all seem to be similar in quality.