Actually not necessarily. If follow that page to the 3600 you'll see that the 3680 is $999. The i7-980X is $999. Similarly the 3520 and 3540 editions were priced below the "extreme" i7 versions. The "extreme" Core 2 and Core i series processors have about as large of a price premium slapped on them as the roughly equivalent Xeon versions do and you also get the ECC benefits with the latter.
There are definitely versions that are not in the intersection (lower i7's and higher Xeons ), but there is overlap in price ranges.
If there were 3620 and 3640 they too would be price below the upper range of the i7 X offerings. The Xeon options can't quite limbo quite as low to roll out $1,000 systems though. However, the top performance end of the i7 series cannot either.
However, want to go to two package socket design (5500/5600)... there is an extra price premium layered on top. One QPI interface versus two will bring an increase. Going to four of them (6500/7500) brings yet another increase (there is still some price overlap if give up clock speed versus 980X )