Build me a simple online purchase management tool

I have a small start-up that manufacturers furniture and home decor accessories. As a part [login to view URL] business we need to work with multiple vendors each dealing with over 50 items. I need an online tool that my purchase officer can log into to create purchase orders using a pre defined catalouge (vendor name, items, rate) and this purchase order will then have to be approved by another user online. They key reuqirements are 1. The purchase order needs should be made using the pre set catalouge 2. New items that are not on the catalouge should be addable but the approver must be alerted to it 3. changes/updates to the catalouge entries must be possible by the admin 4. It has to be online 5. Data must be stored securily 6. Approval of PO must be online me Tif Contactreally intrested then Iwill walk you through the workflow. It's really simple and linear !