Being a photographer who does my own retouching, I bought my Dell Ultrasharp U2209WA secondhand for $125 as a starter. I am now considering my next options, and a 30" IPS is simply beyond my budget/needs, so I'm in the 24" or 27" range.

a) No rush to deal with buying online/long-distance/new, so I'll wait for someone local to sell theirs secondhand. As I like the Dell Ultrasharp line, which specific monitors should I watch for?

b) While I have found the reviews on Prad very helpful, my only issue is how outdated they may become. What was considered "very good" five or six years ago may not compare to last year's "very good" model, and should then be relisted as "satisfactory" etc (unless it really is comparable nowadays!). Is this rating system updated as time goes on?

c) Also, what methods are recommended for doing calibrations?