Have a 2006 Surf Side 34'. Happy with it for the time we have had it - going on four years. Minor issues with coach: water leak in grey water tank, power step motor replaced, switch for living room slide replaced - that is about it. Coach had 9K miles when we got it and it just turned 20K. Sitting is not the best friend to a motorhome. The first thing you will need, are new tires, assuming it has original equipment.
Overall National quality is good. They went out of business in 2008. Having an "orphan" is not a huge problem. All chassis components and many coach fixtures are pretty easy to find, as they are the same as other coaches. Also, there is this company that says they can produce body parts. Ortega Manufacturing | Custom Fiberglass Manufacturing
As mentioned above - lots of good info on this forum from current owners.
Good luck with your decision.