In Europe, I do not think it is possible to find free or very cheap CRO's.
Of course it depends on your country (Europe is big) but in most countries there are enough places to find analog scopes free or for little money, i.e. ham radio swap meets, flea markets, or (at least in the UK) places like Gumtree.
Often enough people find some old scope in the attic/basement, i.e. as a leftover from a former hobby or because someone died.
Sometimes you can get them from schools who may have upgraded to newer scopes but have left the old scopes somewhere in the basement "just in case". Years ago I got several Hamegs this way.
Then there are places like the EEV forum.
About ten years ago, industries have gone to digital and they sell very good analog oscilloscopes by whole pallets at a very low price.
You'll find that most industries (aside from small business maybe) have moved to digital scopes much longer than 10 years ago.
But the majority of these scopes probably moved into private hands over the years, and there are still lots of them around, often without seeing much use or completely forgotten.
High end analog oscilloscopes have become rare ... looks like who has one guard it as a treasure.
Understandable, as analog scopes haven't been "high end" for about a quarter of a century. Roughly since the 90's the high end is digital, and analog scopes were merely lower mid-range and entry level scopes.
In my experience German ebay is particularly expensive (often much more so than other countries' ebay) so I wouldn't focus my search to what's available there. There are plenty of other opportunities, all it needs is putting a bit effort in.