The "Alpine Skiing" quarter was supposed to have the year 2007 on it, but several thousand were made with 2008 on it. That 2 mules in one month. I've bought 5 already on ebay.
To be exact, 40,000 painted versions and 12,000 sets of 14 circulating commemorative coins for the 2010 Vancouver Games have the error.
Maybe the value of these has risen already. The ones I've been keeping track of today have sold for at least $20 each. Theres certainly going to be a demand for these as there is for the other mule produced earlier this month. I bought one myself on Ebay earlier today. Although I'm really not into errors and varieties that much I do enjoy picking up something different now and again.
I bought 2 with sequential serial numbers. Have a bid for 2 more ending soon also. Also, could a mod move this to the errors forum.
I think there are more then 40,000. You can still go to Petro-Canada's and pick these up for 9.95 or something like that. Anyone have a more accurate estimate? I have also noticed price has been going down on ebay.