I don't think we'd get the same bargains as you do in the U.S. My dh and I went to Cosco to see if we could just have a look before purchasing a membership and they wouldn't let us in. So guess what, they lost a potential customer and they were very rude about it.
A current affair program did some cross checking of prices with Cosco and the big supermarkets and they didn't come out as cheap as you would think, so now I just look out for specials in the supermarkets and get it there. The concept of paying a yearly membership to a shop, not even being able to see if it's goods that you would buy, before getting a membership is new and foreign here. I think I'm glad I saved my $60.