Salvage yards. Any Focus mirrors will work on your car from 00-07.
Or you can post a Want To Buy section on here for the mirror/mirrors you want to replace. I have a spare mirror I can sell and I'm sure a lot of other member would too.
Rock auto, like mentioned above, would probably be the best place to buy new IMO.
And lastly, if your willing to spend a little more, SVT mirrors will look the best on your care IMO. If you replacing the mirrors anyways, you may as well improve them.
Hatch Nation #13 : Rally Revolution #13 : ROTM Jan '13
It's Bryan, not Brian
RSVT-170 Build in Progress
Derusting Rusty Build in Progress