Do we really believe this about the U.K.? Could it be a red herring? A few arguments:
A U.K. leg could be later in the race with fewer teams.
Depends on sponsors - Hotels.com, Air Canada (?) or another airline, or other new sponsors.
There are more budget friendly options for accommodations - AirBnB, Home Away or similar. The National Trust (UK) also has very inexpensive places.
In Canada, there are various film grants available. For instance, The Bell Fund. Big Brother Canada received a grant from them last season, so it's not out of the question.
Of course there are a tremendous number of incidental costs involved in production of this show, but I think if they really wanted to go, they could.
Mark is usually very tight-lipped about this kind of info. Why would he reply to this comment?
Also, the casting team just returned from their little tour. Some of the places they stayed did not exactly look budget-friendly. Just saying.