I volunteered in this hostel for a month in exchange for free accommodation (which will save you so much of money when travelling!) Though its not technically in Amsterdam, its only 15 minutes by train from the centre. It is also probably the cheapes...
Official website City Trip Hostels Amsterdam-Zaandam | 10% Discount
Female only hostel, with curtains in all the dorms (yay!). Area is slightly further out but has heaps of restaurants and supermarkets right outside and close to public transport
