I have to integrate C# Windows application with Sage Line 50. (To send all invoice details from application to Sage).

I searched on Google and most of the places it says to integrate Sage Line 50, we need to use Sage development kit (SDK). But it's not free.

We already bought Sage Line 50. But now I want to know how we can integrate our accounting software with Sage Line 50?

I found this URL: http://crmsageconnector.NomNomNow.com/ 

they use Microsoft Dynamics CRM Connector for Sage Line 50 to synchronization of data, as well as data migration.