Wanted: Atari 2600 CX-40 Joysticks

I need some additional Atari CX-40 joysticks for the Portland Retro Gaming Expo. New sticks would be nice, but I'd also be quite fine with used sticks as long as they are in good condition and working order. If you have some you can sell or trade me, please drop me a line. Likewise, if you know of a source where I an obtain several, that would also be useful information.

Does anyone have any experience with these CX-40 clones?

eBay Auction -- Item Number: 140961093364

Thanks,

..Al