Avoid any sites with 'bb guns' in their name.
Those sites are really aimed at kids with no knowledge of airsoft (no offence to beginners) and most of the guns on there are bad.
I've also heard that their customer service is terrible and lots of people seem to have had bad experiences.
For example, I have seen Just BB Guns lies about their products with false statistics and statements - saying guns are really good quality when they're not etc.
The cheap guns on there are not good for proper skirmishing (okay for 'garden wars' & target shooting only), and the "pro" (don't call them that) ones are overpriced.
Like Monty said, I would recommend you look at websites such as airsoft world, Zero One, Pro Airsoft Supplies, Patrol Base, Land Warrior Airsoft etc.
You are probably better off getting a rifle to start airsoft with, as opposed to a pistol. One of the best beginner guns is the G&G Combat Machine M4 - again, go to either Patrol Base or Zero One (cheapest places)