If you do not have to take the shell off to replace the floor, folks take 2-3 years to renovate a vintage AS. That will give you several years to look for the ideal AS for you. In 2006 I bought a 1976 29' AS for $5000. It was in good condition but I replaced the axles, tires, AC, converter, water pump and hot water heater before we got on the road. Think about going with 4000# rated axles.
Last year a couple found a 1977 29' AS that had been in a garage for 20 years. Others buy one only to find that the frame is broken, outriggers are rusted or the floor is no longer intact. Since you have the time, you should be able to find a great AS, make it your own and travel comfortably for many years.