Search on gunbroker.com for your model and see what it has sold for in the past. It's a good way to determine market value.
Actually, states have different rules about selling/purchasing firearms across state lines, but essentially, you won't get in trouble if you have it shipped from an FFL holder to another FFL holder. That's the safest way.
Or, just take it to a gunshow and sell/swap it to a dealer there. You won't get as much money for it, but you also won't be paying for the handling and shipping fees, and it will be less of a hassle. Plus gun shows are fun.