I'd put that money to buying a new computer, a painting, or some newfangled gadget, rather than mutilating myself with the feely-weelies.
But it you're comfortable walking down the street in your short sleeves with strange symbols that can easily be interpreted the wrong way all over your arms, then that's up to you I suppose.
The money that you earn is precious and you must look after it. It all boils down to you asking this question: 'Will buying this serve me in a practical way, making it worth my money?'
considering that you're still a teenager and the master of bad decisions i think that you'd be better off without permanent art on your body for now