I dont't know about cost but I can tell you about the effort required as I have just done my rear and am doing my front one right now.
I took mine out, cleaned, stripped, cleaned, replaced all bearings, cups , seals, rust treated, waxoyled, rebuilt the calipers as well and refitted. It took me 7-8 days on the rear and about the same on the front. Days are only about 6hrs long though![]()