jesus, don't buy a yamaha. strongly recommend getting another hundred bucks together and buying a decent used guitar. the difference is the playability (although there are ways to cheat this, namely a capo) - playing on a cheap guitar will make anyone quit after a month as the strings are difficult to push down and as a result you miss a lot of notes and your fingers will hurt.
sit down in a guitar center and pick up a $100 guitar and then a Martin or a Taylor (or any of the more expensive guitars) and try playing the same chord on both of them. (if you don't know any chords, just pick a few spots to press down on and feel the difference between the guitars- you will see what I mean)
good luck.