I was thinking around $750 would be a good price. Mags I'm not sure, prices are all over the place but they have come down since the federal ban expired.
To sell this rifle legally you have two options..
-A private sale. This is when you sell the AR to someone in your home state. This option requires no paperwork, it's basically a cash and carry deal between two people, he pays you, you give him the weapon. This is also known as a face to face sale and is preferred by many of us here because you save money on transfer fees, plus it's off the record so to speak. You can ask to see the buyer's drivers liscence to make sure he's a resident of MO, but he doesn't have to as you are not required to keep any record of this transaction. With all private sales, use common sense, if a gang banger or a meth head shows up, walk away.
In many states you can actually ship the rifle directly to a private buyer in your home state. Legally speaking this is considered a face to face -or private sale- so it's a cash and ship deal. He sends you the cash, you send him the rifle. I've done this a few times in NY, you have to use a private carrier like Fed-Ex, again no records are required as long as you are both residents of the same state.
-The second option is selling to someone from out of state. The requirement here is that you ship the rifle to a firearms dealer(FFL) in the buyers home state. Then the buyer has to fill out a form 4473 for a background check at his dealer -and pays the transfer fee- before he takes possession of the weapon. Around here the fees are as high as $50.
Where to sell it is easy, use the
Equipment Exchange right here on the boards.
Good Luck.