Higher a plumber? A fair price about 700-1500USD$ and it'll be done in 3 hours. Recommend a Moen Positemp rough in valve as the have easy handle extension kits for just this type of replacement work to account for varying wall thickness. Recommend installing ball valves in your closet and keeping it an access panel. At this point you can install the valves first and then you have everything isolated in case you get into trouble.
That looks like a real degenerate operation. Wouldn't recommend repairing.