HELP! birthday party or new cell phone?

OKAY SO I HAVE THE CHOICE OF GETTING A NEW CELL PHONE WHICH IS THE SIDEKICK SLIDE AND I HAVE A MOTOROLA W490 RIGHT NOW....I THINK ITS A GOOD PRESENT BUT I ALSO HAVE THE CHOICE OF GETTIN A STRETCH HUMMER LIMO AND TAKING 10 FRIENDS TO THE AMUSEMENT PARK! I DONT KNOW WHICH ONE TO CHOOSE! BTW IM TURNING 15. I ONLY HAVE LIKE 3-4 WEEKS TO DECIDE! IM LEANING TOWARD THE PHONE RIGHT NOW BUT I JUST CANT DECIDE!!!!!!! MY MOM THINKS THE PARTY BECAUSE MEMORIES ARE MORE IMPORTANT THAN MATERIAL THINGS AND BLAH BLAH BLAH..SO HELP!!!!