Dealing with Jeppesen in Europe is always a nightmare but it can be done. Forget any online shop though. I always had to use combination of phone/email to get things right, sometimes it takes days to validate your VAT, which is a total nonsense as this can be done online in few seconds but anyway, with reasonable amount of effort and persistence you can get your databases. After that it works quite flawlessly, you get an invoice each and every year, pay it and your subscription keeps working.
Boeing acquired Jeppesen around 2000.
The general consensus is to call them in Neu Isenburg and they will handle it personally.
How do jepps charges compare to Garmin?
https://fly.garmin.com/fly-garmin/
create account, add device, buy database(s)
UPDATE
Apologies, having just looked more carefully at my subscription which is for the above garmin site….it appears that the data is provided by jepps!(international which covers Europe)
If Garmin does provide NavData for Europe (not sure they do), they use a different programmer than the one used by Jeppesen/
We have had many threads in the past on Garmin and Jepp databases.
From vague memory, there were certain databases which could be bought from either source and you got the same data.
A common point of confusion and arguments 
was the way coverage was described. For example, Jepp called “Europe” just the bit west of the Iron Curtain. This is still the case with their plates (terminal charts). You have to be careful what exactly you are getting.
So I managed to get this far:
Now, what hardware do I need to get the 28 day cycle Jepp Navdata to my GNS530?
Google suggests some Jepp Hardware (cardreader) is required for Jepp data or a Garmin cardreader is required when buying from Garmim. It is also mentioned (fwiw) that the GNS units do not have a „unit id“ so data can be „shared“ for multiple units.
You’ll be looking for a Jepp Skybound G2 card reader. You may also want an extra data card if you plan to update from a desktop. I know some people like a spare one so that they don’t have to make the journey to get the card out of the aircraft, home to update it and then back to the airplane to install it. Depends on whether or not you have a laptop and/or live far away.
Data sharing, it depends what you mean. You can swap card around between compatible units, but you can’t just install the same navdata on multiple cards unless you purchase multiple licences, as you only get one download of the data.
