Best internet source for vinyl???

Please help me out here. I've recently got back into vinyl and bought one new lp.
A remastered 180g version of Deep Purples' Machine Head. I reluctantly paid $25 for it at a local hifi store. I was in a bit of sticker shock, but I must say it's a decent recording considering it's age. And compared to cd's average price of $15 it's really not all that bad, especially considering the artwork, liner notes, etc. I've been checking Musicdirects' site, but am already becoming frustrated with lack of titles and some of the pricing.

Also, any thoughts on standard vinyl vs. 180g vs. 200g would be greatly appreciated...