Each car is taking about 6 months of weekends, so at say 24 x 2 x 7 hours, that makes about 350 hours to strip, clean, replace and rebuild each car. The cheapest rate I have found for a decent mechanic in a garage local to me is £30 per hour ($42), so that would put the labour cost at £10,500 or around $15,000.
No wonder we all do most of the work ourselves.
Not for the faint hearted !