"6 Cores for the price of their 4 Cores" Yeah, but you really need them against their 4.
About the comparison table, I did a quick price check (prices in euros):
X6 1100T + HD 6850: 250+150 = 350
Core i7 2600K: 275
X6 1090T + HD 5750: 195+100 = 295
Core i5 2500K: 195
X4 840 + HD 5670: 85+75 = 160
Core i5 2300: 150
X4 645 + HD 5450: 85+40 = 125
Core i3 2100: 115
Did you include motherboard prices? You can't just buy a X4 645 or i3 2100 and let it hang in mid air. AMD and most people that do real world pricing comparisons would do so with total cost in mind.
just grabbing some quick prices in the US
X4 645 $108 + HD 5450 $36 = $144 but there is no motherboard so I'd add say a $57 MSI motherboard and get to $201 (that includes tax and shipping and any other incidental cost the retailer wants to stick me with).
Core i3 2100 $131 but that doesn't cover a motherboard so I'd add say a $103 Asus board. Much more expensive. Is that a fair comparison? Maybe the price is so much higher because there is no supply of fixed motherboards right now? You tell me what motherboard would you put with that i3 2100 if you had to order one today?
Whatever the case you need to include motherboard costs in the comparison or it just isn't accurate.