A repipe for a two bath home with copper pipe and fittings, new shutoffs, supply tubes, etc. will run about (I will email you this amount)plus permits, sales tax and tub faucets. This depends on the area of the country, difficulty and an inspection of the premises before quoting.
It would take a plumber about four days.
Drywall repair would be extra.
If you are only replacing the hot lines, figure about 75% of an entire job.
Forty years is a long time for galvanized pipe to last.
A real nice job would be to replace the line from the house to the meter also.