Well, as I see it you have a few options.

-You could pick up a 'beater' on craigslist.
-You could buy some anti-theft skewers, a chain, u-lock, whatever you need to feel comfortable leaving your bike outside.
-You could buy a folding bike.
-You could give up bike commuting.

If it was me, I would either pick up a beater bike, or just deal with locking the bike outside. With good locks, the risk of theft is probably minimal. I lock my bike outside everyday.