ok, just thought i'd chime in here...

i won't claim to be the best wheel-builder, and i have never read a book or had anyone show me much of anything (read some of Sheldon's website)...

and i don't have a truing stand...

and often pre-built wheels are not so expensive, but mainly for the experience and fun i have built about half of my wheels for the last few years.

just last week: the rear rim on my old MTB (commuter) had cracked and i had already bought a new rim for my FS MTB... so i put the new rim on the MTB (with new spokes) and took the old rim off and rebuilt it with the old hub and old spokes (both 32 hole 3x). the whole job took me about 3 hours including the truing of both wheels (the used rim was not so easy to true and i also had a broken spoke and no new ones - it was sunday)

last summer i built my rear wheel for my MTB and it lasted until the rims were worn true from braking... and then rear rim i took off i also built up last April (hard abuse from extreme trails but not one broken spoke)

anyway, a book is probably a good idea, but you can also do it if you have another wheel for reference and lace up the new wheel/hub like the one lying around (this works for me as i have 4 bikes, most of which have 32hole 3x - one of my fronts is 26 radial but that's easy)

oh yeah, i also just go to the bike shop and show them the rim and hub and let them measure/select the spokes...

if you can true a wheel, then you basically just need a bunch of patience: you have to get the lacing right (and verify _before_ you add all the spokes or start truing)... lastly you need a feel for how tight to make the spokes.

in the end i'm not sure if i save much as it takes me well over an hour to build a new wheel and new prebuilts can be cheap (although re-using saves some i guess)