Intersticial / Full Page Advertisments

I am currently working on developing a game. People will play this game almost completely AFK. However, once an hour a botcheck will appear that they must click. Now, running this game, even with donations, will still be too costly to run without $100 or so out of my pocket every month.
So here is my idea. Every hour when the botcheck comes up, make them look at a full page advertisement for 10 seconds or so before they can fill out the botcheck.
My question is, who would be a good ad company to go with that provides full page advertisements?

See original post by Waizujin