I was able to purchase a DONE4 last year as a US citizen through a Canadian travel agency in Canadian dollars issued by American. I saved close to $5000 and flew business for the price of a coach fare issued in the US. Unfortunately, this loophole has been closed and it's not longer possible to purchase these fares in Canada. I believe you have to purchase in the country of origin - in my case it was Egypt. This can be easier said than done, but definitely can be done. I used miles for the positioning flight to get to CAI - now I'm about to finish the last segments of this ticket and will be ending in CAI and using miles to get back home in next 10 days. Should be an interesting return to Egypt compared to this time last year....