Ive had the info for a while... From memory each jetpak is around $1000 or so ... Realistlcly you would only install 1-2... I'll dig the info out..

I have installed some. They are about as close as you can get to portable spa seat back set ups. They do need a tremendous amount of water flow, so I would recommend only one on a pump, a variable speed would be perfect so you can dial up and down the pressure.
They may cost you a little more then that as they are kind of a pain to install, and require more materials to build the spa.

Most any pool builder that sells Polaris products can get them.

I have two left over from a buy one get one sale they had.
I would make you a deal if you are interested in them. (wife hates stuff in my garage)
What part of the world are you in?

Sent you an email :)