Hi,

Not to put you off but I would have thought that Proxon's wouldn't have the accuracy you'd need and the spindle runout would be limiting to fine detail.

Like you say the price they want for these small jeweller type machines is Madness and for a small machine it wouldn't be hard or stupidly expensive to build a 4 or 5 axis machine like the Roland JWX machines that could hold very high detail.
I've built much larger machines that needed to hold high detail and work to fine resolution, Machine I built for Micheal Marino's for instance works to tight tolerences machining harmonica combs in plastics so a machine with a much smaller cutting area wouldn't be hard or ridiculously expensive.

If you don't have any success with the proxon drop me a line and I'll gladly help you.