Last year the IU bookstore didn't have a single video game, if I recall correctly. You have to be careful too since I know that, at least in my undergrad years at CMU, if you're not careful they may be charging you above the MSRP all in the name of convenience (what a surprise).
Would TIS have it...no, they don't have games either, I'm afraid. But eh, if you need your textbooks and you have to get them now and you can't find any discounts, use the TIS bookstore rather than IU's. It's a bit further away (on 3rd, right off of Jordan) but at least the discount card (free) gets you 5% off, some other deals every month, and what you spend goes back into a rewards program. If you're in undergrad and all it may be best since you can get all of your graduation stuff for free...if you can't find your books for pennis on the dollar, of course.