It's more than super easy to make one for yourself. Other options are:
http://mfg.simundza.com/blog/new-product-mfg-warthog-extensions/
https://warthog-extensions-by-sahaj.com/ - here the price is just ridiculous (after all it's just a metal pipe with ps2-ish male to female adapter :D
http://www.simpit.co.nz/index.php/features-2/projection-display-solutions-2/thrustmaster-extension - ridiculous pricing here as well.
S! =Pedro=