looking for good hotel in amsterdam not to expensive close to centre?

When I have gone to Amsterdam in the past, I just go to the little tourist office in the main train station. You tell them how much you want to spend a night and they help find a place for you. Its real easy and they know all the places.
The only time this may be a challenge if there is a big festival in Amsterdam. Otherwise, this is not a problem, they'll get you a hotel right then and there, same day.

The real trick to to forget Amsterdam and stay in Haarlem, 15 minutes by train outside of the city. It is small, quiet, safe, cheaper, and you are in the city in no time each morning. Get a cup of coffee and drink it on the way to downtown. That alwas takes the stress out of the city for me.

I recently booked a hotel through the site below, and got an amazing deal as well (which is easier if you go off-season of course). The site has great maps too, and if you're within the ring of canals, you're within walking distance of everything you need.

Amsterdam is Great!