Well it definitely happens, although big corporations can be some of the worst to deal with.
I've been the buyer, the seller or broker of a single .CA domain transaction that topped 6 figures, more times than I can count on my two hands. And I'm just one dude who didn't start until 2004, and it took me a couple years to really get into it. I can only imagine the sales I don't know about from the likes of the domainers who got in very early like Jason, Peter, Rick, Wayne, Ilze, Doug, Frank (not mapledots), Samer, etc...
I'm sure you're a great broker, but you are a buyer broker. So maybe raise your .CA expectations and you'll have more luck. It seems possible that your lower priced experiences with .CA have kinda pigeon-holed you into that mentality, thus making it impossible to have a good experience with .CA. As a broker, your personal feelings can have major influence on the buyer side. So be careful not to scuttle a big transaction by hinting at a preconceived value of the domain before you've had a chance to do the market analysis and find out the asking price. I wouldn't hint at any value until you have all the information. I'm sure you know all of that, but just a thought. It may just be that you've had so little .ca experience that there's just not enough data points.