This past year I was trying to track down a couple tickets to the Akron game. A few weeks out pairs were going for a few hundred dollars on eBay (and not for good seats). Stubhub etc were also really pricey.
I waited until a week or two (I think) before the game, and some of the tickets opened up on the
OSU site and I got a pair at face value.
If your nerves can stand it, I'd wait to try to get tickets like that, or just see if you can buy a pair for scalpers outside the stadium on game day. I could be totally off on this (someone with more experience buying tickets on game day can correct me) but tickets outside the stadium were going for WAY less than they were on eBay.