Hi Mark,
It's standard practice that no matter how much you get talked into paying for it -- once you take the appliance of your dreams out of the store the purchase suddenly becomes worthless even to the establishment you purchased it from. Adding insult to injury, I seldom see anything by way of quality to justify the high prices asked.
Personally, these days I'd never think of bothering to trade a vacuum since there's eBay. If a vacuum of a popular brand, though used, is in very good condition it probably will go for substantially more on the internet than you'll ever get from a dealer.
New, nearly new and in great shape Rainbows, Kirbys and other high-end vacs turn up on the market by way of eBay and amazon.com soon enough. It just takes a little patience to wait for one to come along. Keep an eye out. I will mention however that new Kirbys and also Rainbows, I believe, are not covered by warranty if not sold by a seller recognized by the company.
Venson