Ask HN: Some advices for an eprocurement solution?

I am working on a eprocurement solution for professionals and SMEs. Basically, it started with the idea of providing a simple reverse auction platform, but I am now thinking of adding more features (you don't run auctions every day normally and I want this solution to be a part of the long term relationships buyer-vendor so that I can charge a monthly fee).

I now want to provide some smart way of doing vendor and quotes management. Especially, for the quote part I want to create a distinction between the requester and purchaser. Basically, the requester will require the part, the purchaser (or purchase dep.) will receive the request and do a quote request (or reverse auction). Quote request and reverse auctions will be easy as vendors and materials will be in the system already (no need to email people around).

Now, the question is, do you think this set of features, if well executed, is enough as a first launch solution, or you think I would need some more? I was thinking that the "closing" of this process would be a 3 way match, basically the order is closed when the good and the invoice are received and all have the same price.