No idea, although I have heard people mention Ebay.
What are you bringing over that you need that voltage converters for? Check each and every electrical item you want to bring. If it says 100-240 Volts and 50-60 Hz, then you only need a small adapter piece to plug it into the wall (they're pretty cheap). This doesn't change the voltage at all, it just allows you to plug it in. I bought two of them in a computer store and I've also seen them on occasion in the grocery store. So they would be relatively easy to get.
If you have something that is only 120V and 60Hz, then you'll have more difficulty. You can get a transformer or converter to change the voltage but you can't change the frequency of the electricity (the Hz). So be careful about that.
http://kropla.com/electric.htm
Also if you're bringing your tv make sure it can operate on the PAL video system. Canada uses NSTC I think, so if you want to get cable and watch tv here then you'll want to make sure your TV will handle PAL.
Check out these links:
http://kropla.com/electric.htm
http://www.repairfaq.org/sam/pwrfaq.htm
The second link has a list of appliances that might be affected by the frequency problem.
I know you're company is paying for the move, but just be careful that you will actually be able to use these things and not have them burn out after a while.
Haley