LP Vinyl: Quality, Pressing, Label, Weight, Where to Buy ???

Getting back into LP vinyl...its been a long time = mid 70s?  Searching for an educational review on the forum for buying decent quality vinyl LPs...an overview of quality, weight, pressing, label, and best source/location to purchasing (prefer to stay away from ebay as it seems to be hit/miss on what you get). Does anyone have suggestions for an educational review on the subject? 

As a discussion point...I was looking at buying an older LP (vinyl only); I did an internet search = "Faces" - The First Step Album. Online search produces numerous results with prices from $18 to $120...older, used, remakes/repressed, various quality ratings (is there a uniform rating scale), unopened...list goes on. 

Greatly appreciate the forums experience and insight!