The Fox was never sold in high volume so the parts guides are only online:
http://www.hobiecat.com/sailing/part_diagrams.html- and parts (for the most part) are typically a special order. We do stock some things like standing-rigging, but replacement sails or tramps would need to be brought in with scheduled shipments from Europe - or Fed Ex at an extra charge.
The Fox is a blast to sail for sure! But its quite allot of work with the large spinnaker though. If I were to try and compare the two boats..... the H18 is just a fun beach boat that you don't need to worry about when beach landing, where as the Fox you need to always use cradles and take care due to its high performance nature, and the rigging is more complicated - so the Fox has a higher hassle to fun ratio than a H18 (but overall much more dynamic boat, and faster!...but its more rigging intensive, so its a trade-off)