Vitus 979 frames are quite common, they made thousands of them through the several years of its model run, and many remain in use, on the road, despite naysayers about the brand and its bonded construction. Does the "Vigorelli" decals give it a higher market value compared to other re-branded 979's (which also there's a lot of out there) or straight Vitus branded bikes?? Not really, IMO. Maybe a Vigorelli fan might pay a bit more for it to maybe complete his/her collection of Vigorellis, but that's the exception, not the norm.
I'd say the bike might be worth 250 bucks max., in its condition. If you want more money from it, you might have to wait for the next C&V bike boom to sell it........which unfortunately, there are no signs of coming in the foreseeable future...
Now if this was a 979 with the aero section (squashed) "lossange" frame tubes, you will be talking significantly more value, as those are the hard to find version of the 979s. I'd say those could be at around the 350 to 500 dollar level, depending on condition and mounted component group.