E7200- 2.53 GHz- $131.9
E8200- 2.66 GHz- $184.99
E8400- 3.0 GHz- $194.99
E8500- 3.16 GHz- $269.99
From what the prices are (Here, at least), I'd say the E8400 is the best bang for the buck. The E7200 is like the E2xxx series, small L2 cache that hinders performance a good bit.