I'm not 100% but I think most (maybe not all) who sell glitter for baits buy it from the same place. This is because they probably have the best heat stability out there in a poly glitter. There are other options, metal glitter is one, that can be used, but some care needs to be applied if using a microwave. It's metal and if enough clumps up on the bottom it will get more exciting than you probably want.
Jason