You can also rent manlifts, and some will deliver. If you can otherwise do the work yourself (that is, the carpentry aspect is not a problem), I'd do it.
Regarding the roof, I was able to cut my expenditure last year in half. I did all the tear off and disposal myself and ordered all the materials, and ended up doing the garage roof myself. I found a contractor who basically just supplied labor. Note, you will want to nail down the labor before hand if you do that. Some (most?) contractors will want to handle the whole thing and will not quote any other way. FYI, once you get up there and get some balance, it's not that bad (then again, if we are talking 2-3 story house with a steep roof, that's an issue compared to a ranch). Tear off took a day or so, wasn't that bad, and saved me roughly $3000.