Do you have access to the articles of incorporation and bylaws? I would be surprised if the VC's hadn't laid out a process for potentially exiting / valuation while still private. Maybe the current owner left that in place?
My stepfather was a part owner in a small-but-not-so-small business. There were two other shareholders, each with 1/3. Their bylaws stated that the company would be valued annually, along with the process of issuing a dividend.
Long story short, they didn't follow that for several years, then had a falling out, so that aspect turned ugly. Moral of the story: even if on paper, it might not mean much. But if something does exist, maybe the majority owner would be open to a buyout.
If others are in the same situation, is the company perhaps listed on a private company exchange?