bobcat123...Welcome to CGN..as mentioned there is the Equipment Exchange to which you should apply to gain admittance.
Buying from the EE should be no problem with a very low Trader Rating and the proper License but you have to be prepared to pay for the gun before it is transferred into your name and shipped.
You don't mention what kind of gun you want so start a thread about it and build up your post count, this also helps with the buy/sell thing.