Convenience fees for third parties

We're looking into building a site that would facilitate receiving payments online for places that do no have this capability. There's more to the site than receiving payments, it also makes sure there are no conflicts (for reservations), etc. The problem is that companies that offer this service, renting for example, have an on-site price of X. To make it profitable for us we would have to charge X+Y.

The question is: Would this be considered a convenience fee? One of the stipulations on the linked site states that the fee "is assessed by the merchant that provides goods and services to the cardholder and not by a third party". Since we're a different entity, would that mean that we could specify whatever price we wanted? In a way, we are resellers for these companies that offer the service. Can we be considered resellers, and if so, could we just list price Z on the website (where Z = X + Y) or would we have to break it down into X and Y? My understanding is that these rules apply to one merchant, with the goal of preventing price discrimination based on payment method, and not for cases where two different merchants are involved. So, can Visa / MasterCard dictate how we should structure the price?

Thanks.

I am not a lawyer, so do not take this as legal advice.

It would seem to me that this is really a discussion between you and the company you are reselling for. If in your terms of service agreement you state that you are allowed to set prices, then I would think that is ok. The risk is angering the company who is reselling through you if they feel your "Z" is too high.

Personally I would just make it a part of the sales conversation. I say this because companies know their customers well. They will let you know how high a price can go. They may even be willing to cut their price some to keep it at a certain rate but still sell online.