iphone 3gs in VERY GOOD CONDITION( or may swap for iphone 4) !

HI.I have iphone 3gs which is 3 months old fully boxed in VERY GOOD CONDITION and its jailbroke in perfect working order. im selling my iphone due to upgrade to 4s however i may swap for iphone 4 with money. i had no problems since i bought it and still has screen protector on. also it has 16gb capacity and comes with its original accessories, charger etc.