J.B.
You would have to assume that there is something majorly wrong with the bigger house for half the rent. You know...the whole "if it seems too good to be true then it probably IS too good to be true" idea. I wouldn't let falling in love with this listing change your plans. If you haven't actually seen the place, then go ahead and check it out, but do so with a VERY critical eye and ask why they aren't charging market rate. There's probably a reason.
That said, you CAN get out of a lease, you J. end up forfeiting either the security deposit or last month's rent or whatever.