An example from continental Europe (Germany):

Cessna 172 (wet): € 100 per hour (Hobbs-time) on average
Fuel: 1 litre of Avgas 100LL can cost up to € 2
Landing fee: € 5 at a small airfield (up to 2000 kg MTOW), € 20 at a larger (regional) airport (there is no such thing as a free landing anywhere in Germany).

X-countries are rarely a problem airspace-wise, only sometimes in the region of international airports. Largest problem in Germany apart from costs is disappearing airfields, particularly around larger cities. “Noise” is also a problem and virtually all German GA-aircraft have had silencers fitted at great costs (some airfields levy a hefty charge at “noisy” a/c).

I think LH has a stake in Eurowings; the latter has been operating flights inside and out of Germany for quite some years now. I was on a Eurowings aircraft yesterday with an LH flight number, and the welcome-in-bla-bla announcement said “… Lufthansa flight operated by Eurowings…”