your gonna have a bitch of a time finding hardcore vinyl here in the USA.
here are some online shops you should check out
imorecords.co.uk
www.24-7vinyl.com
vinylsearcher.com (mostly classic hardcore, pretty pricey)
if you cant find any records you want, you can go here
www.discogs.com
pretty much every hardcore vinyl record ever made can be found here, but it's peer to peer sales, and pretty expensive. But worth it.
just remember, Vinyl is FINAL, fuck them blasphemous CDJ audio destoying software crap, Hardcore till I die