Getting the most bang for your buck requires that you buy the cheapest model. Because 10-20% performance increase is about equal to doubling the price.
I really don't think so, and neither does
Newegg's listing of Core2Duo processors. You can go from an "bottom-rung" E4300 to a "high end" E6600 without doubling cost, and that's quite a bit more than 10-20% performance difference too. Even if you wanted to make the argument for the absolute highest-end C2D processors being costly, you can lodge the same argument against AMD's offerings too.
However, that really wasn't the spirit of what i was trying to convey, so let me retry...
For $189 you can get an AMD X2 4600 AM2
For $183 you can get a C2D E6300 LGS775
Now, in essentially every gaming benchmark, the E6600 at stock speeds will beat the 4600+ at stock speeds to the tune of about 20-30% depending on the game. CPU-specific (aka synthetic benches) will often show the gap to be even larger.
The only price variable between the two now is system board. And for running stock speeds, the cost difference between a basic AM2 mobo and a basic LGA775 mobo is neglegable at best. You can get the absolute-cheapest AM2 board for about $45; the absolute-cheaest LGA775 board is $42.
In reality? Price vs performance, Intel's C2D has the upper hand in most cases. Now, there comes a point where the AMD offerings are too far below Intel's performance level for the C2D, and then they start competing with the PentiumD series. In that arena, AMD takes over again, but not by a significant margin and not enough to justify the cost of the platform IMO.
Hopefully I explained myself better this time.