I was going to ask the same Q.... how much was that plane worth before the job was done, and how much is it worth afterwards?
I was quoted 48k euros for installing a G500 in my
panel, by Socata. This included a GNS430W. UK installed prices are not much lower by the time everything is taken into account. With my plane being worth about 140k euros (not the 200-250k euros asked for in the typical "in denial" advert
) it might be worth doing - if it made it go faster