Hi Stefan,
IIRC, they weren't much more than £130 when they were new and considering you can buy a K1 brand new with the 5 year warranty for £129, I'd say more nearer £100 would be more reasonable. At the end of the day though, if they can get £130 for it, they should go for it. Might be worth amending the listing to accept offers though and if they get £90 - £110, accept it.