These can be done in my view, my local garage, has one in every other week, he strips it down to rid of the parts that are broken, then works back out to rebuild again buying all the parts he needs, sometimes when i take my car in and check out his "projects", they are just car shell's entire side of the car need to be bought, its mad! but hes profiting, so it must be working ok!
But its easily said when you have the experience, and he usual only has the exotic cars, SL55's CL55's Cayannes and the like.
If its your first, id stay away, if you're going to use a garage to help, it could be good!