http://www.acousticsounds.com are re-issuing 25 great jazz classics in 45 rpm. Very serious stuff, remastered by Steve Hoffman and Kevin grey. This site also has a ton of other jazz, and some classical.
Uh... I would avoid Simply Vinyl. Their stuff sounds terrible and is overpriced.
Acoustic Sounds is a great source, Music Direct (www.amusicdirect.com) is another. Audiophile Int'l (www.audiophileusa.com) is yet another. There are many others but these will get you started and in addition to a large inventory these guys know what they're talking about.
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