1st, if you're thinking about selling becasue the tranny slips a little, and you don't want to spend $$ to get it fixed, check Oursl.com's web-site and call web-site's owner to get a fair estimated value for the car. Assuming it's got some body/under paint rust here & there, but not so much hidden rust that it's prohibitively expensive to restore, it's worth at least $12-$18... as is. Interior wear/tear looks to be minimal even... has it been refurbished or is it the original interior? How many miles on the odometer?
Sounds like the dealers you've talked to are either totally ignorant, or the preverbial "used car salesmen" types... I'd guess the latter.