Hello
Yes and no... In fact, the ad module can provide product price and let seller and buyer to be linked but there is no payment automatic procedure. Payment and delivery are carried by the seller after the buyer has contacted him through his profile or the buy now button on the ad.
Otherwise, there is a Store module which can be useful to sell digital products as ebooks or coaching videos and more. Here you can connect paypal or other payment module in order to let your members buy those e-products.
You see more can modify the Store module in order to make it more ECommerce style, but there is some work here.
Regards