I currently have a BJs membership, used to have a Costco membership. While I don't like paying for the membership I definitely realize the benefits. Besides bulk buying regular non-perishable goods I've found significant deals on electronics. To dkelly27's point I think that's where the real savings are found.

I know of someone that purchased a vacation through Costco's program and said it was well worth the money. I also know of someone (in Tennessee) that only gets their gas from Costco (it's significantly cheaper).

So, in the end I guess it all depends on what you're purchasing to see if it's worth the price.