So wants a motorcycle

Okay, my boyfriend wants a motorcycle really bad...He knows that I have 8k saved up for other things. Right now I am a substitute teacher and I just got my BBA, so I'm looking for a decent job. I am willing to let him have 3k but he is asking for 4300. How do I tell him that I'm uncomfortable with this. I  would feel better if it was going towards his books or tuition for school.