I wouldn't buy anything older than five years myself... thoese Oder units you are looking at may have cost to incur you have not considered beyond the cosmetic obvious things..
Some items that would require attention and cost you dollars if you can't do the work yourself are:
1. Brakes and wheel bearings. If worn out gonna cost
2. Leaf springs and bushings on the 2001 and 2006.... age and wear and tear has surely caught up to them and will cost you lots of labor dollars if you can't do job yourself
3. AC and other appliances on older units might be hard to get parts for if needed
There is nothing wrong with a nice used unit that has been card for and properly serviced and maintained... but if you buy an older rig just because then you might be unhappy later..
Just saying