The European price I got on the retro fit kit was €7,445 ex tax/shipping. An exciting offering but certainly not cheap!
The new FCS at €31,250 is €2773 (before tax/shipping) more than the race package equipped F20c.
Sounds to me that it's hard to justify the kit on a used boat as it would be just over $10k before any installation labor. The kit does sound very interesting, I would love to see some pictures.
The flying phantom is €28,260 for comparison.
Please remember although the F20Carbon FCS is Euro 2,990 more than the Flying Phantom the F20 FCS hulls are 12.3% longer (6.2m), its beam width is 6.6% wider (3.2m), its mast is 8.8% longer (10.45m), the main sail area is 16% larger (21m2) and the spinnaker sail area is 16% larger (28m2). So you do get a lot more boat for your money!