Please find the attached for Magic Quadrant for procurement and sourcing software. I think that i will contact them and compare functions with our requirement. The present, i have seen the procurement and sourcing software open source named "Coupa" be software as a service seem like a SAP Ariba but minimal investment.
I have two choose for implementation for this project that first, In-house development and then, using the commercial software included Open source.
I will response you again if i have answer about the solution which meet to our requirements.