With GameStop's Pro Day sale today, preowned discount for Pro members is increased by 10%, and they also have a 4 for $10 ($4.99 games or less) going on until tomorrow. If you're a pro elite member, that's a discount of 30%, and at the checkout, the 30% is taken off of the $4.99 and the 4 for $10 deal still takes off $2.50, bringing it down to $1. If you're just a Pro member, the games will be $1.50 each.
Unfortunately, their website is a pile of garbage, I spent many hours over the past week filling my shopping cart for this day and it would not let me cash out. Tried everything I could possibly do to make it work, nothing, and the 1-800 number couldn't help me at all, they said I'd have to place the order at a store. So, I just got back from the store with my list of 112 games and the poor unfortunate souls at the shop entered them all individually into their computer. Then they did it again because they messed up a couple of the games and they had already finalized the order at that point. Anyways, chances are the website wasn't working for me because of the insane quantity of games I was ordering, and even trying to reduce the shopping cart down to 40 games didn't help either, but if you're ordering from the website anyways and want some dirt cheap games to tag on it, well there ya go.
The deal is shown on the 3rd ad banner in the preowned section