Triple channel really isn't that much more - around $50, and remember you do get another 2 GB. Other factors could be the reason why it the i7 build is more expensive - the main parts that really differ are the motherboard, CPU and RAM.
The CPU is around the same, both at $300 each or so.
Depending on which motherboard you buy, the X58 is cheaper or more expensive, mainly more expensive but if you decide to for for a higher end 890FX board it will cost just as much, if not more as a decent mid-ranged X58 board.
RAM-wise, with the i7 it is $50 more, but it helps future proof it in a sense. If you're that concerned with triple channel pricing though, an i7 860 will perform just as well as the i7 930 in most applications, and the i7 800 uses dual channel memory instead, and any decent P55 motherboard would suffice.
However if you have your heart set on the 1090T, it's a pretty good processor in its own right.