IMO, "MSRP" is meaningful and something you WANT to know when you're talking about the high end and/or the rare stuff like Padrons, Opus X, Añejo, etc.

However with your regular run of the mill domestics, I figure a "fair" price is what they can be purchased from via the large internet retailers like:

CigarsInternational
Famous-Smoke
SmokeAll
SeriousCigars
AtlanticCigar
JRCigars
Holts

etc.......

As far as MSRP for the high end stuff, there's a great pinned thread on CigarPass authored by MilesMingusMonk.