I shop for books at Amazon so I'll give you a couple price examples from there.
Using your example, I'm guessing the Dutch text editions go out of print quicker than the English text editions. IT (English text) hasnt gone out of print here BUT if you wanted to buy a new copy of the first printing in hardcover, it would cost $162.37.
The Colorado Kid is out of print - the cover price is $5.99 US. The cost of a new copy of the mass market paperback starts at $43.00 (used copies start at $6.45)
Tabitha King's Small World is also out of print. The cost of a new copy of the mass market paperback starts at $34.50. I don't know what the original cover price was - probably somewhere around $5.95.
Sorry, I don't know how to convert US dollars to euro.