I buy CD's - mostly used, rated VG or better, from Amazon, eBay, and Discogs.
Over the past year or so I've been finding the VG rated discs to be much better
than they were in prior years - and I attribute that to customers making noise and
docking sellers with punitive feedback - and many sellers are just going with a
VG rating rather than Like New - simply lowering expectations. And it seems to
be working.
Also, so many are just ripping to FLAC or whatever, and then putting the
disc up for sale.
And as for locating music I like, I'm subscribed to rateyourmusic.com,
allmusic.com, and various music services. I look at charts, I read comments
on sites (that are worth reading), I speak with friends and get their take,
if I like a certain producer for example, I'll look up his/her work and then
parse it through rym for example.
Also I listen to radio - WFUV here in NYC, I think is pretty good. So is
the Columbia U station 89.9, and WBGO - jazz all the time. No ads
on any of these. They all play a lot of interesting new stuff during the
overnight, when I tend to do my listening.