We have a place in England, UK that sells White Glitter Heat Transfer Vinyl.
I tried to put a link to the site here but my post was blocked.
I'm not sure how it compares in price to what you pay for your vinyls in the US or whether this company even ships to the US but I just thought I would make you all aware that it can be obtained
Hope that helps to some degree,
*Its called Glitz Flex Garment Vinyl*