I know this company it’s 100% legit – Probably only works for you on price if your in the UK? (based on shipping etc)
But £9.95(including postage) for an Official Dino/Mascis shirt! I doubt your get it cheaper new…
http://www.loudclothing.com/itemlist.html?searchquery=dinosaur%20jr
http://www.loudclothing.com/itemlist.html?searchquery=mascis