E-Procurement Solution

My organisation, which currently uses paper tenders, is actively considering adopting an e- procurement solution to include e-tendering, e-evaluation, e-contract management and vendor management. Having done a little research, I have identified a number of potential providers: Asite Solutions; BiP Solutions; Bravo; Due North; EU Supply; European Dynamics; In Tend; Science Warehouse to name a few! I would be grateful for any advice from any organisations who have undergone a similar journey and in particular how the various solutions were evaluated. Clearly there is a difference in price for each of the various providers but the quality element is the tricky bit! Technical support/training will be critical for us as we are a small procurement team and this is a significant step change for the organisation. Many thanks in advance.