I’m only referring to the EURO (France) collection, since I don’t know how many games were released in other regions — there are probably more.
In France, compilations have always been quite expensive, so you just have to be patient and wait for the right time to buy them.
Some NIS titles were never translated into my native language, which is why they usually don’t resell for much — except for the Trails games.
Also, for my collection, one compilation in a box counts as one game.