It is a shame the G500 won't talk to any other IFR GPS (
AFAIK). If it did Garmin would have a much bigger market.
The G500 represents brilliant value for money really. The unit itself only costs about $14,000, and gives you new eHSI, RMI, DI, AI, MFD and will drive your AP. Try buying an HSI and MFD and you have already shelled out more than a G500. Of course add in a 430 at $6000 increases that to say $20k plus fitting. £40k sounds pretty expensive??