.NET Developer to build a payment service

We would like to build a service in C#/.NET that exposes some RESTful endpoints for us to consume. The service will integrate with several different payment gateways (for example Stripe, Braintree Payments, etc.).

The service's job will be to abstract the integration with these specific gateways so that the same API endpoints can be called on the service to perform certain payment operations, for example, Authorize, Charge, and Refund.

We will provide a full-service specification after agreeing on hourly pricing and start date. If you would like to apply for this job, please let us also know if you are willing to perform a very simple test project also.

We would like someone to commit to working on this full time. There will probably be further services to build after this one.