Everyone gets all worried about the upgrade issue. Don’t let it stress you. If you’re pretty sure you’ll want to upgrade, a 250 is actually one of the best things you can buy. Unless you reduce it to a smoking ruin, you’ll be able to unload it quickly for nearly what you paid for it. Any other bike, you’ll probably take a depreciation hit.
Also, the 250 is going to have lower operating costs because it uses less fuel. The small size will also be nice for navigating campus traffic. At least where I went to school, roads were narrow and prone to a lot of twisting.
It doesn’t matter how cool the first bike you buy is, you’ll want another one. I have a very cool bike, a 750 Magna, and I’m still tempted by things like the 250 Ninja.