I am looking for a bike for getting around college. My campus is kind of hilly but not too bad. I have been getting around on an older mtn. bike, but the teeth on the sprockets are breaking off(rust), so there is pretty much only one gear I can ride in b/c all the others slip. I don't want to spend anywhere near what I see many others spending on bikes, probably about $200 max, aroudn $100 would be even better. I kind of want to get something that I can get a round on faster, w/ skinnier tires, easier to get up hills. But I want to be able to ride off curbs and cut across grass/gravel and want something that is manuverable so I can weave around people/ cars etc. From what I understand road bikes are really made for going straight very long distances. So i don't really want a road bike or a mtn bike. I think that cyclocross bikes look good but like I said i can't spend more than about $200. I am fairly mechanically inclined, is it possible to get an old road bike or something and put different wheels on it, etc?
What would you reccomend I do?