is it possible to rotate out banners?

What I mean is,

Lets say you get an offer from a CPA network or banners from an affiliate program and you have them on your website. Is it possible to get 2 or 3 offers that have banners. And set each banner to rotate on your wordpress site?

I use the flexibility theme and I currently have a banner for a cpa offer that Iam promoting. But I just had the idea of testing different offers on the same website and testing different banner placements so I wanted to figure out how I could put different banners in the same area on the website and have them switch out per visit.

ex:

visitor 1 goes to [mywebsite].com and sees a blue banner on the side of the page in the sidebar widget. visitor 1 leaves website.

visitor 1 comes back to website 1 second later and now sees a red banner on the side of the page in the sidebar widget.

Does that make any sense? Anyone know of a script that can accomplish this? Preferably not too expensive as money is extremely tight right now :[.

I am willing to figure out how to code it myself if that's what it takes to get it cheaply I just need to know if its possible and where I would start.

G