Hi jackthedog: A very nice looking machine. It's a 979 Mk II — distinctive for the fast back seat tube design that used a grub screw to fix the seat post. I have a Mk I.
These are niche machines. Horror stories of catastrophic de-bonding of the interference fit on the tubes and lugs has scared a lot of people off them. De-bonding has occurred and has been recorded around the internet. The horror stories have not proved to be accurate. But apparently a lot de-bonding has occurred. Many of these cases may be due to corrosion in the interference interface of the joints, and subsequent failure of the bonding agent can be a result.
I paid about $50,000 yen/$500 for a complete bike just over 14 years ago. It was a mixture of Campy Record and Sugino 75, with a Mavic 310 headset (as yours appears to be), Mavic GP-4 rims, brooks saddle, Sugino 75 brakes, Cellini quill stem and bars and a Nitto Crystal seat post.
They are not gaining in value due to a number of factors. (1) They were not rare. They came as frame-sets, and both individuals and companies built them up. A number of names were applied to them in addition to the Vitus branding. As a result, they can come in a multitude of various parts and groups. (2) Some people wanting a machine like this turned to the Italian Alan. This bike two was epoxied, but instead of an interference fit, threaded tubes were screwed together. (3) Around the net there are warnings about not changing the rear spacing such as in a steel frame by cold setting. (4) One company in Vancouver, Canada offered a repair and restoration service for Vitus frames. Any interested party should try to contact "Guywires". They have gone very quiet for over some 5 years or so. In other words, people expect that the machine carries some risk, and perhaps they cannot be repaired. And if they can be repaired by somebody the question remains for many people, 'Is it worth it?" it They can be lovely frames with nice geometry, but YMMV — literally
What size is it? I may be interested. You can PM me if you are interested.
Cheers — Lenton