Some things to consider:
If you try to sell broadly (e.g., on the internet), the trademark holder will find you and request the site to remove your merchandise...which they must do by law. Even if all the trademark holder does is tell you to stop, they have very effectively eliminated your market.
If you try to sell openly (e.g., craft shows, local shops), the entity may prevent you from doing so in order to protect itself from harm. They, too, must remove items from display if so requested by the trademark holder, and if you are selling within the college area, there will be college reps walking around looking for 'unofficial' products. It's big money to them to stop you.
If you try to sell quietly (e.g., by word of mouth), chances are you won't be found out, but you likely won't sell much either. The more you sell, the louder the buzz, the closer you are to the college itself, the more apt you are to get noticed...and stopped.
You could probably lessen the potential "damage" by including a disclaimer that your item does not represent any "official" product, nor does it have the endorsement of 'so-and-so' college, but even before considering the legal/illegal aspects, you need to decide if it's worth the hassle. Best of luck.