A friend of mine is a US dealer for the big names and he does e.g. G500 installs for far less than it costs in Europe – even allowing for freight and VAT.
I don’t know why this is.
In his case I trust what he tells me, but when it comes to the advertised “installed” prices I suspect there may be clauses allowing them to charge more if they find a can of worms. Otherwise, they would get a self-selected customer base with a lot of people flying old wreckage with 20kg of wiring going back 30 years 
Yes, that’s one of the points regularly overlooked … especially with older planes. I once watched Avionik Straubing pull out about 2 kg of dead old cables from behind the panel of a Bonanza once – before they could even start to install the new stuff!
When I do an avionics project with Straubing, I get a quote for the hardware in USD and the work at hours * EUR/h as fixed price. The hardware cost I research on the web and make sure it is not above street price in the US. Even by US standards, Straubing is a very large company and gets good discounts so with their markup, costs are still reasonable. I actually pay them in USD for this which means they don’t have to charge a “cushion” for FX changes. On top of that I pay some freight and VAT, that is inevitable.
The hours required is very similar and the hourly rates are not very different either. In the US you also have differences between the Bay Area and North Dakota.
So all in all, I pay more here but not substantially more. If I did the work in the US, I would have to pay VAT on the installed devices when I fly the aircraft over. A lot of pilots don’t declare this improvement of the plane but that is a felony in most jurisdictions. Normally you have to declare and pay at your first landing in the EU (often Wick, Scotland) but by arranging it upfront, you can get approval to continue the flight and declare at your final destination in the EU.
By the way: these are the new WAAS antennas i let them install. A GA-36 in the front and the very expensive CI-2580-200 combined COM/WAAS-GPS antenna (3rd in line). That antenna I could have got for $ 975 (plus german VAT) … and I paid € 1300 for it in Germany,
First test of LPV approach in VMC after installation of 2 GNS430Ws and 2 new antennas.
Anders wrote:
The German AIP supposedly (I do not know how to access the German AIP) contains the following text:
I find it easiest to use Eurocontrol EAD
ENR 1.5 Holding, Approach and Departure Procedures seems to have a section on EGNOS and vertical guidance – 1.8.4.
