The big problem with jumping into a potential money pit is if you do not have enough money left in the kitty to address any issues that come up.
This does not mean that you will have any problems but if you stretch your budget with the purchase price, any problem may mean the coach will just be sitting unused and nobody will be happy.
For me I would definitely be looking at replacing the mattress and maybe all of the furniture. If there are any lingering odors, maybe replacing the carpet also. Then you are looking at the possibility of rubber items in the suspension and drive train deterioration. Now, besides the updating of the electronics, what about the batteries? Of course the roof AC units may be on their last legs.
Mileage is only an indication of how much time the coach spent on the road. It is NOT an indicator of how much time the coach was used while sitting in an RV park. ALL of the systems could be well used/abused even if the mileage is low.
Basically if you have enough extra money sitting in the bank, an older RV may be a great buy, especially if you are able to do most of the work/upgrades yourself. To max out your budget on an older RV is a foolish move and may lead to a huge disappointment if you now own an expensive vehicle that is continuously in need of expensive repairs.