So you want to customize Sharetribe?

Ah, you should probably do some research or ask on the open source community discussion. Apparently the braintree integration that is present isn't well supported and only works with US based companies. And paypal is only supported on sharetribe.com.

Consider fees, escrowing, legal requirements, the ability to take one payment (from a buyer) and split it into two transactions (one to the marketplace, one to the seller), and the currency/countries you need to support.

There are a number of payment providers out there, Stripe is one I'm familiar with, and they support a fair number of countries.

Have you decided on a payment provider yet?