Lee,
Unless that GT235 has been trashed and not well taken care of, $1000 is a good price. It's a garden tractor and will have a heavier duty transmission than the LX172, plus it's a hydro where the LX172 is a gear drive. And Dave is right also, it that LX is in decent shape that's a good price on that one. Myself, if both were in similar shape, I would take the GT any way over the LX though. The GT is a few years newer and will be a stronger, more durable tractor.