Well the problem is any type of payment system out there is not going to do that that I know about.
Ebay doesn't even do that. You can charge a fee to place the ad but payment from a buyer to seller happens to the seller not you therefore there is no way for you to get a cut. I buy on ebay all the time. ebay is not collecting my fee. The payment provider sends payment to the seller of the item.
I hope you follow what I am saying. Any of the normal payment providers the guy being paid is the seller not the actual site.
If there was a way to do what you wanted I would have already done it considering the vast amount of features I have added into Classifieds over the years.
The only way for you to do something even remotely what you want to do would be for you to actually be running your own payment service where all payments go through. I am sure specific site stores which process there own payments might be able to but no idea personally as I have never ran an etailer site.