No - definetly not going to try doing it myself as I wound need to climb up on the sunroof roof (its not a flat roof)to get to the upstairs gutters above it - would probably end up killing myself !!
We have a 4 deb detached with sunroom - all glass with solid roof.
I always paid €25 -until 2 weeks ago the window cleaner called by to say he's dropping his price to €15 as there is another guy competing with him on the round.
He's probably charging most for the guttering. As he's coming today (Saturday) I would just pay the €100 and then presumably you won't need the guttering done for a good while again.
Meanwhile you can find a cleaner just for the windows a lot cheaper (or do them yourself).
You can't rob the man either, there is a whole days work there, break it down into an hourly rate, using his equipment, ladders etc, as you say, risking his neck, €100 is fine. I would def pay that for someone to do all that for me.