I accidentally washed my iPod nano 5th Generation and didn't want my girlfriend to know. I had an engraved case so I needed to keep the case. I talked with a repair shop, but they didn't sound hopeful that they could do what I asked for a reasonable price. So, I decided to do it myself. I found an identical iPod (minus the engraving of course) for a low price, and just replaced the guts.
The repair was not too bad. I had some trouble with the wheel on the new one because I didn't go down far enough. I also had trouble getting the camera stop out on my original iPod. I had to grind it down until it would slide under the lip of the case. I also lost one of the screws and didn't have the proper screwdriver size. Those screws are like eyeglass screws. The whole process took about 3 hrs., but after having done this twice, basically, I think it could be done in about 1 hr.
Be careful when removing the camera stop, if it breaks it is a pain to whittle it out. The iPod nano 5th Gen. does not come apart as easily as the videos show. There is an adhesive holding all of the parts together so it will take some effort to remove the pieces. Also, if you don't already have one, get a a phillips head screw driver from here or an eyeglass screw driver will also do.