MarketPress - Include different payment gateways for different users


I currently have a site set up for my girlfriend's mobile therapist business. She often deals with clients she trusts but is expanding and getting new clients.

I think a useful upgrade to Marketpress would be the facilty for guests (new clients) to the site to only see the paypal option. I.E She would like to be paid before she confirms the appointment.

But existing members/users to have the option to pay for the treamtent before hand via paypal or manual (ie cash upon delivery). Could integrate this with membership plugin maybe?

It's basically having different payment gateways for different users. Hope others think it's a good idea and useful for their site!