I'm planning to visit Costco this weekend to have a look around and may be buy some stuff. It appears you can signup online:
http://www.costco.com.au/Common/Membership.shtml
Any idea if they email you a temporary print out pass immediately?
Do you need to be running a business in order to signup as a business member? Or an ABN (sole trader) is enough?
Cheers!
once you signup, you take the confirmation email to their membership counter and they print it out for you right there.
Just take your driver licence or any other valid id.