I want to purchase 2 roundtrip tickets from San Francisco, CA to New York, NY. (FOR MID OCTOBER, 2010) I realize buying in advance would be cheaper most definitely, but the thing is booking in advance is very hard when it comes to figuring out what will happen with a work schedule down the line. How much more expensive is it to purchase two months away from the date? Rather than booking it now? What do you think? Need help! Would be greatly appreciated! Thank you 