Hello Miss Kitty,
Go over on AdButler and signup anf then signup for the adbutler banner rotator ( its free )

This will allow you to have a banner rotator on your site that you can add banners to, also you can create advertiser accounts so they can login and check the stats of their banner.

The site is really self explained but as far as the prices, I would charge accordingly to the site traffic.

One of my sites HarleyBabes uses the adbutler and to see what I charge for advertising click on the advertising link once you enter the site. Now keep in mind that by site gets no less than about 5,000 visits a week, my advertising is actually low cost because I try not to break peoples bank but thats to help them out.

Since you do have the site you do then I would charge a little more tham myself and not offer so many banner ads. Example: Get 10,000 banner adimpressions for $2.85. The great think is that adbutlrt allows you to set banner at per impressions or per clicks, so an example of the clicks with 10,000 banners would be $4.85 as you are sending your visitors away from your site.

Now one thing adbutler has the right to show 10% of their banners in your rotator but thats fine, with the low cost advertising I have on my site I still have made about $300.00 from the last 3 months with adbutler banner rotator.

My 2 Cents

HarleyBabes