Nice site. I'm wanting to build a similar bike. The Vanilla looks pretty good but is disc only (which I'd be ok with if it comes down to it). I see you were able to afix a tubus swing to it. Care to shed any more light on how you did that?
What i've found so far:
rock shox Tora XC SL Coil – seems right $170 at Mikes bikes steel steerer tube normally $232
marzocchi 33 TST2 $280
Fox Vanilla 32 $390 140mm and disk only
Magura Odur $325 highly recommended ('08 and '09 are the same)
I'm leaning towards to Magura or the Rock Shox.