Integration was once a major issue when selecting and implementing a spend management solution.  Fortunately for everyone, except maybe I/T consulting firms, the solutions and infrastructure capabilities have increased to the point that integration between platforms and ERPs is significantly easier and cheaper.  

Our advice for most customers is to get their program up to an activity level that would justify the integration. Scanmarket supports most common integration protocols using webservices and has integration capabilities for all major ERP and P2P platforms.