Thanks guys, but there's one problem (one more thing I forgot to mention):
My friend is going to buy this keyboard in a specific store. This store part of one of the bigger music store chains here in Sweden. I checked out their website, under "used", and found nothing. The closest I got was a Roland DisCover 5. No used Motif and the other of the more "top-end" used boards were just too expensive.
So, in short, it's best with a new keyboard even if that degrades the quality a little. This is most likely also only a temporary solution, until he can get a band together.

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Robert.