How old is too old?... older NICE rig or newer budget rig.

I recommend you go with the old, better built rig. I think you will be much happier with something that is better built. With any used RV, you need to make sure the rig was well cared for. You need to make sure all the required maintenance was done. You need to see if the coach is having problems with paint checking. You need to determine if the owners are the type that takes good care of their things. You should have an oil analysis done.