Looking at this scientifically, we could agree that bang for the buck can be represented by the forumla:
value = bang / buck...
Where bang = 0 - 100 representing overall IQ, capability, and ergonomics
And buck = $ spent to obtain the camera
And value = the normalized value of the purchase (the bigger the number, the better)...
SO.... Suppose a 5d2 (which I own) has a "bang" of 90, but cost $2400 for the body:
value = 90 / 2400 = .0375
And a 7D (which I also own) has a bang of 85, but cost me $1800 for the body:
value = 85 / 1800 = .04722
Thus illustrating that the 7D gives more bang for the buck.
BUT WAIT THERE'S MORE!
Someone just gave me a Rebel XT (AKA 350D) for free. It takes great pics...
value = 60 / $0 = infinity.
Wow looks like the Rebel just kicked the 5d2 and 7D's butt. Hey don't glare at me, it's math and math don't lie. 