Ha, that's a can of worms
Prices will range widely depending on the sort of finished materials you select. I think most of the guys on this forum do end up building much of their projects themselves and many of us (me included) are weekend hacks and not "professional builders". This forum is a great resource to learn and the people here are more than happy to help!
Of course, it comes down to having the time and perseverance to tackle these large projects yourself. In most cases, these projects take most of us 2-3 years from start to finish. For me, it took 2 1/2 years working most weekends and 1 or 2 weeknights every week. It's hard to find the necessary time with a family. It's fun but does get tiring over such a long period of time.