You might try a Priceline bid for the airport area. I have gotten the Courtyard Marriot over in HoofDorp a couple of times in the $45-55 per night range. The last time was in Oct 2006 for $55 per night. Shutle van to the hotel is free but they do charge 5 Euros for the return or you can just walk about 200 meters from the hotel and catch the bus that runs from Harlem to AMS for about 3 lines on the Strippencart. I also seem to recall a area of the termimal that had a bunch of recliners set up where you could snooze for free.

The Holiday Inn by the RAI also has good rates and can be bid on via Priceline for about $60-80 per night, I have stayed there many times and it is close to the tram and NS Train.

Be Safe
DFWBOB
Now BWIBOB soon to be DCABOB in Feb2008