If used 17-yr-old TC shows $9k on NADA... for one in great condition as far as looks go (appears to have not been used much at all), would you pay NADA or how much less? To get a good deal.
Over the years I found all those estimating sites to be biased. In few minutes you can compare yourself using ebay or local craigslits. Let's say you find Mercedes MY that kbb or NADA values at $10,000. Few minute search will reveal that you won't find such model for less thatn $12-15,000. Do the same with Chevrolet or Ford car. The $10k valued cars can be have whole day long for $8000 or less. Campers are rare, so the value is tricky, but I usually go on ebay and do "sold" search.