Even though you live 1/2 mile from UCIrvine, its a good idea to have a bike to get around the school (its big enough), rahter than walk all over the place.
My suggestion is to go down to the local diso**** store (Sports Authority, Target) and get a single speed cruiser bike for $100, spend $20 for a basket to put on front, and use that as your daily commuter and grocery-getter machine. Get a good lock, too. Might also want to buy some spray paint to "ugly up" the bike's frame to make it less desirable to thieves. Keep the Trek in the apt. for those longer weekend rides.