As of October 2015 our apartment has been sold, and is no longer for rent.

The agent who sold our apartment is Klok Real Estate in Amsterdam.

It will always be cheaper if you can contact an owner directly, but if you are left with going through an agency, they are one of the better ones. As well as sales they handle rentals, their English is no problem and they are used to dealing with people coming from abroad.

Best wishes on your stay in Amsterdam.