If you were to sell on gunbroker, the buyer pays the shipping fees from FFL to FFL. You pay the gunbroker fees, but they aren't that bad, considering the exposure you get.
Selling off armslist can be tricky. Locally, sellers have gotten a combination of genuine and counterfeit dollars. And, does IOWA allow private party transactions?
Not much info for a decent response.
Private sales are still a protected right in most states.
There are a few states that have infringed on the Second Amendment and do not allow private sales.