To hook up to all the hotels mentioned, they are only really talking one block from Nova Centre to Scotiabank Centre, as this section would gain them access to the Prince George, and then all of the other hotels mentioned already link up to the Scotiabank Ctr. by the existing tunnel/pedway system.
I don't know what tunnels go for these days, but to me $10 million seems a little steep for such a short run.
That said, the west side of that stretch of Grafton isn't anything to look at anyways, why don't they forgo the tunnel idea and just build an elevated pedway alongside the buildings on the west side? It would fulfill the functionality aspects and cover up some of those ugly buildings in the process. This would make the Prince George access a lot less expensive as well...
https://www.google.ca/maps/@44.647035,-6...CSAc9KLNz7HDt-UGTYW4Q!2e0!7i13312!8i6656