LPT: if you’re the type of person who doesn’t wear branded clothing. Use a wholesale website to buy Gildan, Hanes, FotL, etc. branded plain color t-shirts, hooded sweatshirts, etc for far less than you would pay at a store.

For clarification: I understand the wording was a little confusing. By “branded” I mean a company brand or logo plastered on the clothing everywhere.

My top suggestions would be shirtspace.com, jiffyshirts.com, and bulkapparel.com

Edit: as many have suggested. Crafting stores like Michael’s do carry these shirts as well. But generally just one type (usually the most basic) and not as many colors as an online retailer. But still a great option.