Maybe GWR could get a few at a knock-down price for the Night Riviera fleet?!
Don't think there would be anything knock-down about it.
The 'inactive' coaches in Canada are little more than empty bodyshells with bogies that were acquired by Via Rail as a job lot with the rest of the Nightstar stock - the Nightstar plan was abandoned in the middle of the production run - so you might just as well go to CAF and ask them what a follow-on run for more of the new Scottish sleeper stock will cost.
But that will have to wait until the GW franchise comes up for renewal in 2019, when I expect bidders will be asked to offer options for the Night Riviera, including new stock or fitting power doors to the Mk3s.