Well you need the heatsink since the 635 in the combo is OEM. The cheapest retail Athlon II X4 NewEgg has is the 640 and will set you back an additional $10. So 635 with a cheap aftermarket heatsink or 640 with stock cooling doesn't really make too much difference, you're paying about the same.
Some fair points, though. For example, if I was building a budget system I'd probably get an Athlon II X2 instead of an X4, don't really need quad core for web browsing and other basic stuff. Would probably also go for a better integrated GPU like the 785G or 880G instead of lower-end chipset and discrete GPU. But for what you get, it seems like a pretty good deal to me with the combo savings. Add a 500GB HDD and you have a quad core system with 4GB RAM and discrete GPU (albeit a pretty low-end one) for <$300. That isn't bad at all in my book.