you should try ebay.
****Answer**** Depends on what your selling.
$50
At your local field to a new player, or online.
In used condition? around 10 dollars.
It depends on which gun and what shape its in. In general, about 50-80% of the price of a new one.
The purpose of a paintball gun is to fire paintball pellets, to mark opponents in the game of paintball.
A paintball marker is a paintball gun. It is just called a marker instead of a gun.
There are numerous sites to sell your old and used paintball guns. This includes, Ebay, Pbnation, and Sellmygun.com. Though be warned, you could get ripped off easily.
There are a few places where someone could purchase a Smart Parts Ion paintball gun. A store like Sears, and websites such as trademygun, and ultimatepaintball, all sell Smart Parts Ion paintball guns.
If someone is willing to sell you one for a penny, then yes. if not. never in your dreams.
No, do not expose your paintball gun to water.