First off as said above forget anything from Just BB Guns they are toys not suitable for skirmishing. Probably break on first outing and will definitely have you seriously outgunned.
The G&G gun you linked to however would be an excellent starter gun, if you want to save bit of cash there polymer rather than metal guns are just as good.
As for pistols forget about them for know and concentrate on you primary and other kit such as batteries charger and mags. Pistols are fun but often end up just as holster fillers. You can always buy one later, spending the cash on a better primary or kit would be a far better idea at your level.