Is there any documents or projects that can be downloaded that caters for implementing a Sagepay Payment provider into EPiServer 7.5 Commerce?
There are no official document about integrating Sagepay Payment provider into EPiServer Commerce. But you can reference the Sagepay API and sample payment providers provided by EPiServer (DIBS, PayPal, Klarna, DataCash) to implement yourself.
Sample payment providers can be dowloaded from the following page:http://world.episerver.com/Documentation/Commerce/?id=66797&epslanguage=en&version=7.5
(See Guides section in right column)