JohnWebcams - I'll be sending you some info via email. I'll include more info on the traffic for you.
tigermom - I've used those formulas with non-Internet business, and I think some of them apply if we were selling the business. But since these are just two traffic pumps out of many sites we have, I thought that pricing them based on the quantity/quality of traffic would make sense. An auction might be interesting, and it would be a fair way to deal with multiple buyers.
I've gotten some good ideas from this thread. Thanks again to everyone who's contributed some feedback. Any other ideas appreciated too.
Simon