I feel like I took a bike maintenance class at REI where they covered truing a wheel. That may be untrue, but it sounds possible. I do know that after I paid REI to replace a broken spoke, then paid them to replace another broken spoke, then broke another spoke, I figured if I ever wanted to do anything with my money other than give it to REI so that they could hold my wheel hostage for a week at a time, I should learn how to do it myself.
Once you can true a wheel, you are more than halfway to building one. I used Sheldon's instructions and Roger Musson's Wheelbuilding Book:
Roger Musson Wheel Building Book Reviews - Mtbr.com
I've also read Jobst Brandt's The Bicycle Wheel, but I had already built a few wheels by that point.
Starting with a front wheel, or a non-dished rear wheel may be easier. Since I always use hub gears, I tend to get away with very little dish on mine, which makes life simpler, but a dished wheel isn't that much more complicated. It's just a couple extra steps when measuring.
We used to help people build wheels at my bike co-op if that's what they needed, so that's another place you might check (not my co-op, it's gone, but check out local ones). If nothing else, the co-op may have the tools, which is nice if you don't want to spring for everything up front.
