These days, the very best possible sat nav solution is free if you have a smart phone. Using either Waze or Google Maps will cost you nothing and keep you abreast of traffic in real time with incredible accuracy. They are both constantly updated with the latest changes to road infrastructure, too, so there are no costly upgrades to make. Either will provide better navigation even than the priciest integrated system or aftermarket, dedicated navigation unit.

A smartphone in a cradle might not be the elegant solution you asked for but there's no real shortcut to getting your integrated system updated. So at least give Waze or Google Maps a try before paying that pretty hefty fee.