Have you tried Gunbroker.com? 

http://www.gunbroker.com/

I can't think of any other source than gunbroker.com as I am assuming you're in Canada.  Here in the states I'd suggest gun shows or even Cabela's as they sell used guns.  CZ are nice guns.  I have one in .375 H&H,  Good luck

I'm in the states actually but can't seem to find one of these. I've tried gunbroker / gunsamerica, etc. Just hoping someone knows a secret that I don't.

After I posted I just Googled CZ 550 Lux and it came up with a number of possibilities for you to check out.

Sorry about the confusion there in my initial post. For some reason CZ has apparently decided to stop bringing the Lux model to the states in anything other than the 7mm magnum. Even their nice little Battue rifle is offered in only the 300 Win Mag (with a 20 inch barrel if you can imagine). I understand that magnumitis is at it's peak here, but it's gone crazy when a guy can't even get a 30.06 with open sights anymore.

For the record, I have owned a small number of magnums and have nothing against them, but too often I've found the negatives to outweigh the positives with them.

Haven't checked them but will give them a look. I see Remington still offers the BDL which may fit the bill nicely. I just "need" another rifle for a backup.