A good glass store will have their scrap sorted by coe. Same with a seller on eBay or elsewhere, as long as it is a reliable seller, and they note the coe….but it doesn’t hurt to start a conversation with the seller to get a feel for their knowledge. There are several glass sites online that sell fusible glass scraps.
Most any experiences with glass, even failures aren’t a total loss, that is how we learn and grow.
Scrap glass is an excellent starting point in glass fusing, I think.