I have seen a presentation of Smart team and while I was not using Inventor at the time (rather Solidworks) we were told that this file management software could handle any other types. So one could assume that it would handle Inventor files. I have also see Desault systems EPDM which both of these interface/network with purchasing and other departments along with the engineering files. I currently use the vault workgroup and have been told that the vault professional is similar to EPDM. I have not see it in action, so I can only go on their word.
I don't know if this info is useful to you, but I would take a look and maybe outline what it is exactly you and your company are looking to accomplish and then find the software that best fits that need within the cost constraints you are given.
Best Regards,
Scott McFadden
(Colossians 3:23-25)