Consider hacking a Microsoft Dual Strike (new on ebay for 9 bucks). The advantage is that it uses a 20k pot, but only turns about 1/4 of the way (ie, 5kpot).
note: I haven't used one because when I could get my hands on a 5k pot controller, I didn't know how I wanted to hack it.
Anyway, people have had great luck with it and some say they don't even have to align the joysticks!
I've heard that they allow hotswapping the pots also.