Replying to New bike for campus

my hardtail bike was stolen from outside my apartment the other day, so i am currently walking to class every day which, frankly, sucks. so i need a new bike. i live in boulder and go to cu, so my commute is a slight hill one way and downhill the other, but never more than a 15 minute ride max, then anything else around town is completely flat. im really low on cash at the moment (just bought a new dh rig last week which is overkill for campus), so ive been looking on craigslist and have been thinking about getting a single speed/fixed flip-flop hub bike: good or bad idea? i found a lightly used bigshot single speed for less than 150, which is the most i could spend right now, so would that be a good option?

i dont really know a lot about road bikes/track bikes/etc., but i know that if i tried to get anything complicated (like a full road bike), it would either be really old and probably need a lot of work, or would just be shit components which would need to be replaced in the near future