Willowtip, Deathgasm, Dark Horizon, Barbarian Wrath-Vinland, Dark Symphonies, Red Stream, Ajna Offensive, Total Holocaust Records, Moribund Cult, CAH Records, The End, Razorback Records
I buy a shitload of cd's off of E-Bay . Also, www.redstream.org has good prices, www.centurymedia.com, www.cdbaby.com, and I buy a bit of local music from band's sites. Sometimes I get some good cd's at the local CD/DVD Exchange. I don't know of any killer stores around my area, so I buy my shit on-line.
I get most of mine from The End.
I also have ordered from Blackmetal.com, Red Stream, Century and ebay.
CDBaby is good place to get CDs, I haven't tried it for any that would be discussed here, but they do handle mostly indies.
Mostly Relapse Records, Metaldisc.com if they don't have a certain band I'll check thendsrecords or labels such as Uniqueleader. I only buy from amazon.com if I can't find the cd anywhere else being that amazon charges way to much for cd's.