Jeff -- If you bring $100 in cash, you'll find a practice round ticket fairly early in the day on Washington Rd. I think the scalper's price varies from year to year, but you shouldn't have to pay more than that, and likely you'll pay quite a bit less. (At least, that's what it says in "Amen Corner."
When I was there in 2005, I saw lots of people selling tickets outside the gates.)
A freebie from an exiting spectator for a few afternoon hours sounds good if you're trying to cut costs, but if you want to take in the full scope of the place in one day, you need more time than that. Good luck -- it's a great experience.