There are THREE of the GCTs on eBay right now with 'buy it now' prices of $1740 - $2150. Of course, the highest one DOES include free shipping....
http://www.ebay.com/sch/i.html...minal&_sacat=220
Perhaps if you list yours with an opening bid of $1000 - $ 1200 you should easily sell it this week.
Personally, if I was your LHS I would jump on the offer you gave him. Especially if he is sitting on several of the (cheaper) Union Pacific pieces, unable to move them. Which station will be more valuable in a couple of years do you think?