Good cheap acoustic guitar for beginner

Hey guys, I'm a complete beginner and I signed up for classes.  From what I've been reading, and advice that some of my friends have given me, I have decided on getting a steel stringed acoustic guitar.  I don't have a lot of money to put on it though.  Somewhere between 100-200, I might be willing to go a little over 200 if a quality guitars don't exist in that price range.  Basically wha'ts the best steel stringed acoustic guitar for the buck?  I know there are some cheap steel stringed acoustic guitars in Best Buy and Target some even under 100 bucks.  Would you guys trust those guitars?
Also maybe I don't need a guitar at the moment?  They provide guitars for the classes but do you think it's necessary to buy one for practice?
Thanks a lot in advance