I was supposed to build up some mountain bike wheels for my friend, so I could get in a little practice in technique. Unfortunately, the spokes he wanted to use cost $28 for a set of 36, and because of different spoke lengths, I would have to buy at least 3, maybe 4 sets of 36, costing him the almost the same as a local pro build up. I am giving him back his rims and hubs, but before I did, I got to see first hand what a modern mountain bike hub looks like if it has disk brakes. I was shocked to see the flanges are 5.25 cm flange to flange, for a build that will have to be as strong as possible and subject to tons of tacoing force. As reference, an old campy front hub measures 7.0 cm flange to flange, for a wheel that will have fewer forces acting on it.
To get to the point, If you live in South Florida and are willing to pay for spokes and nipples and provide hubs and rims, I will build up a set or a single for free.
Garth Libre in Miami Fl