No, it's not difficult at all. It's just a little pricey using shippers like FedEx or UPS.
By the way, there are a few local supplier in Europe that sell the same products available in the US (except for spare parts from Van's).
No, getting tools and materials in Europe is not difficult.
- all US companies ship oversees. It's a bit pricier, since you have to add international shipping costs and VAT in your home country
- Aircraft Spruce is also present in Europe (see www.aircraftspruce.eu). Service is as great as in the US: the prices are typically 1 EUR = 1US
- you can get US tools (drillbits, wrenches, etc.) at some specialized companies in Europe - just google
- and least but not least: it is always a great excuse to go to Airventure or Sun'n Fun, traveling with a big suitcase