<edit> oh wait, you don't need this info anymore. that's what I get for not reading the thread. </edit>
On both of my visits to Amsterdam, my nights were comfortably spent at a youth hostel in the south end of the city. If you don't mind sleeping in a room with 3 to 9 other people, the hostel is a great deal.
Bring ear plugs, towel, washcloth, soap, combination or key lock, and a reasonably sized piece of luggage and you'll be fine. You'll have to make your own bed; it's the Linux of hotels. Breakfast is included and opens somwhat early. Make reservations as soon as possible in advance, but if worst comes to it, you may get a room if you walked in that night.
City Hostel Vondelpark
stayokay.com
+31 (0)20 589 89 96
E 29/person/night - 4 bed room - includes breakfast
E 26/person/night - 6 or 8 bed room - includes breakfast
E 24/person/night - large dorm - includes breakfast
7:30am reception open
2:00pm rooms available
10:00am check out
lockers @ E 0.20/hour until the 2:00pm check in
There is also
another one on the north end of town, but I haven't tried that. It sure beats sleeping in the train station, from what I hear. Have fun.