It listed for 29,000. He had it for 15 to move it. It is a new '09 model with full warranties. There was a 2010 model on the lot that also listed for 29(for reference) that he couldn't go less than 25. With the trade in of my 7 yr old similar style RV I needed about 6000 cash. Trade in was right on spot with blue book. Could have probably gotten another 1000 if I had sold it outright, but was ready to move.
Legally, you have to dump at a dump station. Most all of the camp grounds have dump stations, and our home septic system has an access cap that works for me. As far as "how long can you go?", I guess it depends on what type stuff you pack. We spend about a week at a time at most in it, and when we don't try to be conservative, I usually have to dump the black and grey tanks every 2-3 days. I am sure you could go a week if you were trying to stretch things. Same on water. I will have to check and see what the water tank will hold. I usually work off of city water.
Food all depends on what you pack. We are usually not trying to pack for long term, but when hurricanes come, we pack tons of nonperishables. So a week would be no problem.
Propane will last a long time if used for cooking. If you are running the gas furnace, you will have to refill, but I never use the furnace (SE Texas) so I really don't know how long. If I had to bug out with full water and empty tanks, I am sure we could stretch a week. If I can find a water hose and dump tanks, we could probably pack in enough food for a month.
Hope that helps, but there are guys on here that might chime in who are much more adept at this stuff than I.
Doc