Like anything, something is only worth what someone is willing to pay for it. That being said I sold a "nice" 2M duplexer last year. New price was close to $1500, "ebay price" was around $600. After schlepping it to several hamfests and having numerous tire kickers, I finally let it go for $350. Probably could've gotten more online but did not want to deal with shipping such a large heavy item. Dayton has it's own price strategy, starting high Friday and ending low Sunday, and depending on whether you're willing to take it back home if you don't get your price.
Seems there aren't many repeater builders around anymore so you just have to find the right guy. Being 220 limits your audience by quite a bit but if you're going to find that one guy, your odds of finding him probably aren't better than at Dayton.
Mark K5LXP
Albuquerque, NM