Vintage Sports Fashion offer a staggering range of authentic, used soccer products, as well as a smattering of merchandise from other sports. Many of these shirts are vintage in nature, dating back to the 1980s or 90s.
Their website is fairly easy to navigate, but they fail to provide detailed photos of their offerings, though they do describe the condition in text format, making it a bit of a gamble to know what you're going to get. So far, however, I have been quite pleased with the quality and condition of the items I have ordered. Prices are often quite higher than other outlets, including shipping rates (which go up the more you order, making larger orders unappealing) so I only shop for must-have items here.