I am looking for an ad serving solution.

Here is my list of wants:
1) Provide the potential advertiser with a real time measure of what sort of traffic I am providing
2) Give the advertiser the ability to sign up, purchase and manage their advertising assets online through a control panel of some type
3) The customer should be able to specify the price that they want to pay with PayPal - CPM or CPC or days
4) When there aren't any customers to fill an ad space, I should be able to create a default campaign with ads from a large ad network (Tribal Fusion, Value Click, etc)
5) Geolocation would be nice
6) Frequency capping (number of impressions per hour/day/week/month and per user session) would be good
7) Written in PHP/MySQL
8) Image upload support

I have been looking at Ad Manager Pro and it is very, very close to having everything, but it doesn't allow the advertiser to name their own price.

Does anyone know of a piece of software that can do all of the above things?

Thanks.