BigWilly:
I got one last week at the Canadian Tire (the flagship store) at Church/Yonge (across from MTV. I forget how much I paid for it but it was under $30 I believe. I used it for the first time last weekend on some really intricate wheels and it worked awesome! Just make sure you get a liquid metal polish, not a paste as it (paste) doesn't like to stay on the mini powerball very well and is hard to apply. Worked great though for me, the wheels were really shiny after I used it. Another tip, use the Torque setting for your drill, not speed, as you don't want it too fast (or the powerball will tend to skip and it's hard to control).
Just go to this Canadian Tire location and you'll be set (they have a really big aisle of car supplies too).
-Dale