Read the old posts on how to call Yves' sailing school for Mystere parts. As to your spin, consider an AHPC mid-pole ring. It's a great design. You can get an entire Capricorn spin hardware set from Fun in the Sun (Robbie Daniel & Jill Nickerson). Find a spin pole locally to save shipping. For the spinnaker itself, start with used F18 spin (unless you have lots of cash and want to buy all new).

I have a bunch of parts left over from 5 years of Mystere-ing. I'd sell a set of rudder blades, lower castings, a bag of cam parts, a set of gudgons and rudder pins, and probably more. Send me a PM if interested.