I only bought and found them in flea-markets quite recently as I wasn't collecting them earlier.

Indeed Druillet keeps being one of the only to do comics that way. Nobody even dares to do that kind of crazy, time consuming compositions today, most creators seem afraid it wouldn't sell. There's a strong dogma of economic rentability that's constraining creativity, even in the world of arts and comics. Sad, as I don't want this tradition to disappear.