I've considered building, but after a bit of research I've concluded that building your own really doesn't save much money (granted, there would be a lot of satisfaction in doing it) ... I suppose quality mass-production and economy-of-scale keep the prices of commercial Dobs relatively low.
There's a lot to be said for letting the experts do it, anyway. I'm the kind of handyman who measures thrice, and still has to re-work :(
Check out eBay for Dobsonian Telescopes. There are several up for auction right now. BTW, I know absolutely nothing about telescopes. I just happen to like eBay.