Pricing is a rough estimate, and I am just pricing the CPU+mainboard. If you are looking at a bufget build, and everything else is the same, then the CPU and mainboard will be the only differences. For mainboards, I went with Gigabyte. Why? Cause I like Gigabyte, and they make both AMD and Intel mainboards with similar features.
Intel:
Mainboard - GA-P55A-UD4P - US $185
Processor - i5 760 - US $205, total US $390
AMD:
Mainboard - GA-890XA-UD3 - Priced at about $140, has similar features to the P55 above
Processor 1: Athlon II x4 645 - US $ 115, total US $255
Processor 2: Phenom II x4 965 - US $ 160, total US $300
Processor 3: Phenom II x6 1090T - US $ 230, total US $370
When comparing the builds, if a person has a limited budget, for the Athlon II build, that person would have an additional $135 to spend on a graphics card. With the Phenom II x4 build, that person would have an additional $90 to spend on a graphics card. And with the Phenom II x6 build, that person would have an additional $20 to spend on a graphics card.
$135 could mean a whole performance level difference in graphics. Hell, even $90 could mean quite a bit of difference. Sure, $20 is not that much more difference, but it still is money in the pocket.