Thanks for the mention Leester!
Bodywork, rust repairs, it's specialized work like most work on cars. This past weekend, I painted my son's Datsun 240Z and it came out great, like the Lancia did. Getting the hang of painting but have to say, if a 61 year old accountant like myself can do this after just watching a bunch of youtube videos and doing some basic research, so can most people. As I reported before, I am painting in my 2-car garage with second hand compressor and fan, and maybe $350 in miscellaneous lumber, screws, plastic and other supplies. The gallon 2K urethane paint for the Datsun came to less than $200 and it's stunning. I did have to do various typical rust repairs to the rockers, floors, rear hatch and fenders. With only one year of experience, a basic welder, very basic tools and some sheet metal, I can now do such repairs invisibly and solidly. So, in my experience, it's not complicated or hard, but it is very time-consuming and, at $50-100 an hour, that is what adds up quickly. And of course in Mercedes' case the cost of replacement panels.
I am currently rebuilding my Lancia engine. Some work will be done by a machine shop but the rest (dismantling, checking condition, deciding what needs doing, and re-assembly) I am doing myself. The engine is in good shape, but I am replacing all valves, springs and seals, piston rings and connecting rod bearings but all that is coming to less than $800 in parts and outsourced work. The whole rebuild will be around $1,200 maybe and if I would have had to get new pistons + overboring, add maybe $800. A Pagoda engine rebuild does not have to cost much more, if you do the work yourself.
But, like anything, get it done by a professional and the costs will add up very quickly. I still do think that, depending on the extent of rust, that can be far more costly than mechanical repairs, as most others here have commented.
