To be honest, I'm skeptical whether it's really worth it for an average household. The membership doesn't come cheap, and you really have to go regularly for it to pay off. Sure, the bulk packages are cheaper per unit, but only if you actually use up the stuff before it expires. I know people who bought things they didn't need just because it looked like a bargain at the time.
The thing is: Costco is designed for large families or small businesses. If you live alone or with one other person, you'll quickly end up with spoiled food or things you don't even want to eat. Even if you're saving on the per-kilo price - if half of it goes in the trash, that's not savings anymore. Take a look at which products you actually need regularly in bulk quantities (frozen stuff, grains, dry goods) and calculate it beforehand.
For the Munich area, it could work out differently, since you might have less selection from cheaper wholesalers. But try going there first with someone who has a card - lots of people take a guest with them. Then you'll see for yourself whether it makes sense for you.