We too bought a used class A; 2006 National SeaBreeze LX, 33 foot. We've had it 18 months now, and have done the following:
1. New tires all around, $3000
2. New fridge - went with a residential - $1200 (my option)
3. New front TV - $350 (my option)
4. Suspension mods - $1000 (my option)
5. Fluids - $500
6. New transfer switch - $600
7. Re-seal roof - $400
8. Defog Windows - $900
9. New A/C compressor for V10 - $450
Total is $8400 so far - BUT - we love the MH. Most of these costs are not annual costs (tires come to mind) and some were my option to upgrade. I'm budgeting $3000 per year for required maintenance. We'll see if that is enough as we move forward...
Al