The RCEXL seems to work just fine on my FS-52 at 10kRPM. I see it listed as good for 12kRPM on some sites.

Yes, those are Pounds Sterling for the Runtronic ignition. I think you could subtract VAT, but it's still expensive. There is a company in the US that had(?) them and the basic unit was 200USD. I emailed and never heard from them. I got mine off Ebay for $24, it even works!