I also love discogs but have had to wean myself off of it. NYC has tons of record stores, but these days I try to only buy when I'm traveling. I found a chain in Indiana (Joe's Records) which is shockingly overpriced, but has some great stuff in the dollar bin, stuff like The Carpenters and Glen Campbell, which is perhaps ubiquitous in Indiana and which they haven't yet figured out they can gouge hipsters for.
Like Martin, I'm all vinyl and mp3s these days. My main criterion for an LP is: will I listen to this a lot? Occasionally I'm wrong, especially with new bands.
I try not to spend more than $20 for any record, but every so often I'll find something I can't pass up, like the 1974 edition of Nuggets with deadhead cover art.
I also sold all my vinyl, years ago, and regretted it. I managed to re-buy most of it, but it led to idiotic moves like spending $30 on the Murphy's Law green vinyl album and realizing, the moment I played it, that I am no longer 15 years old.