Such a frikkin' deal!! Wish I'd done that at your age!! Go for it!!!
And when it's time for your solo cross-countries, do some research first to find airports with the best fuel prices...

. Seriously.
I haven't flown in a couple years, but I've heard that (as others have said here) that it's generally nudging the $3/gal. mark in the US now, but like auto gas, it varies somewhat from place to place. Look around, make a list.
Don't forget landing and parking fees, either- ask if they cover that or not. Some fancy-dancy FBOs will actually charge you to have a line boy wave you in to park, even if you're just getting some fuel and hitting the head. Sometimes said FBOs are the only one available at a given airport. This sort of information will influence your flight planning, if you're serious about saving money. There's also headset, fuel sampler, navigation tools, manuals, textbooks,emergency stuff, Sic-Sacs- will you have to pay for all that stuff, too? All of that stuff can be found pretty cheaply, but it's an expense worth factoring in if your money's tight.
Whatever the case, not having to cover the aircraft rental or instructors' time is a HUGE discount! Very good way to get your PPSEL! And an awesome way to serve your community!