The only problem with an older leak free unit is the decals. I think I'm going to remove mine a section at a time and paint the straight decals. Eternabond it right away to keep it leak free. Water is the enemy. I bought my TT new and my MH used. Money wise, I have about 1-2 years of depreciation of a new one in mine.
I suggest you look on Ebay to get an idea of actual values.
I remember those Apache plastic popups. Growing up we had a Scamper with the blue vinyl cloth. I think there would be a market for a smaller Apache style unit with the solid plastic sides.