Dunno, really. There have been rumours that the PWU (Power Workers Union) is behind them, but nothing really solid, and its clear that however it raises funds, WCO's core membership are local NIMBY's.
However, their new book, Dirty Business, shows multiple links to Energy Probe, Lawrence Solomon's faux enviro group. From the EP website:
(September 9, 2011) Dirty Business, a new book that focuses on wind power’s impacts on Ontario’s power systems and rural communities, features three Energy Probe directors (retired banker Parker Gallant, economist Michael Trebilcock and Globe columnist Margaret Wente), and a past executive director (Tom Adams).
Given the obsessions of Wente and Co., it isn't surprising that they might have allowed some of their columns to be reproduced for the volume. More intriguing is Parker's Gallant's role as the book's "Contributing Editor", which suggests some kind of consultative role in its creation. He is also, as it turns out, on WCO's BOD.
As background, Energy Probe seems to have begun life as a kind of quirky, right-wing group devoted to promoting free market solutions to environmental problems. As you can see from the Star article at the bottom of the link, back in the 1990s Solomon managed to convince the right-wing Donner Foundation Canada to kick in several $100,000s (perhaps as much as $1.6 million) for various projects, and their name still appears on the Energy Probe Research Foundation's donors page. So these guys are pretty well-heeled
In any case, whatever EP might have started out as, it has in recent years degenerated into your standard-issue AGW denialist group, or at least serves as an outlet for Mr. Solomon's curious notions on the topic.
I'm not sure this gets us much closer to answering who funds Wind Concerns. But perhaps it will cause a few people--journos, maybe who are in a position to get answers--to at least ask a few questions.
PS. As of this mornin, WCO had not filed for third-party status here, which limits the manner in which they can spend money to promote their cause..