If you go to the Craftsy BOM class - there are pages and pages of samples of what people have done - some used just two or three fabrics and their quilts came out to be quite lovely. You could definitely use fabric from a thrift store - a dress, couple of shirts and backing ... sometimes less is more!
Do you know about
www.quilter'scache.com - all her blocks are free. You can scroll through pages and pages, find a block that you like each month and do your own BOM. Also Bonnie Hunter at quiltville.com has just started a Block of the Week that will run for 6 weeks - you don't have to do it that quickly just copy the info and work at your own pace.