Sig Pro SP 2009 Value???

I just purchased a New Pro Sp 2009 about a month ago. How can it be "NEW" if they were discontinued a good while back? I didn't do any research on this weapon before I bought it. However thats not what I am asking. This is the first Sig I have owned, and I really love the way it shoots and feels. It is very accurate. I have always been a 45 ACP mostly Glock guy, but I am sold on Sig. I would now like to sell/trade this pro for a Sig in 45 ACP.( By the way whats the most compact Sig in 45 ACP) and an average price new/ used) What can I expect to get for this Pro SP 2009? Factory night sites and 2 15 round mags. I do know that the Pro models do not have much resale value, So Iam wondering what to expect (ballpark) value wise? I know if I go to a gun dealer I most likely won't get very much on a trade.

Thanks in advance for the help.

Most guns are going 20 to 25% under retail if you go to a gun dealer as they have to resell it and make a buck there to. A gun that has no collectors value can go even lower. Don't know the Sig line well enough to help you any farther. Good luck.