You could buy something like
this. In case the link doesn't work, it's a Mio 320B for $98 on ebay. (No idea of the seller, just thee Mio320). The screens are excellent and very daylight readable, and come with a mount, and power adapter.
Add to it, either
a) a pocketfms one year subscription for €150, and always be uptodate, or
b) or a PocketFMS Fusion licence (which doesn't need to be renewed annually) for €270.
Worldwide maps and data, 6 months updates, lifetime weather, and 6 months weather+
dp