You rarely need a pass to stay in a hostel and it's a waste of money to get one. The better hostels are always the small independent ones that won't accept your card. Below are sites you can use to compare prices and sometimes make reservations. A lot of places only book by phone.

www.hostelworld.com We used this one in Euope and Asia. It lists a good variety, worldwide.
www.hostels.com is reputed to do the same.
Hostels of Europe is more focused so it prolly has a better selection.
VIP Backpackers Resort some New Zealand options
Budget Backpacker Hostels more kiwi digs
Hostelling International is a big, boring, institutional chain with locations in many countries. Who knows why you might want to stay here. For the U.S. Headquarters call 202-783-6161 or email hiayhserv@hiayh.org It's about $25 for HI membership.
This is the dominant cheap stay in Southeast Asia ($2 - $10 per night). You can prolly haggle a price lower but we never explored this tactic to it's fullest. Our average nights were between $2 and $5.