Its funny you mention this because I was just looking at some numbers last week. I have a 2008 non-unibody MBP, still under apple care. 2.4Ghz, 4Gb ram, etc. I figured hey maybe I can get some cash for this one and buy a new fancy model. So I check apples tradein/recycle thing and it says they will give me $350 (LOL), I then check ebay and its like $400 if flawlessly perfect.
So 2008 MBP = $3,000 (top of the line) 2011 = $350. I should have learned my lesson and did what goldmercury does.
Bought my MB Air for $1k after Bing cash back on eBay 2 years ago. Sold 2 months ago for $750, new MB Pro for $1200. Gotta shop smart.