Good Lord man! There are people online giving their I-teeth for that gun! Fire heavens sake DO NOT, I repeat, DO NOT trade that gun in to a dealer!
Look at the prices that gun is bringing on Gunbroker. Advertise it locally and on other Internet forum classifieds. You'll probably gey enough to almost buy two stinking Glocks.
If you don't have any luck selling on your own or you don't want to mess with it, I'll easily pay $100 more than whatever the dealer will give you on trade.