You need to be a member...,

[Silverobama]

Two weeks ago, I was about to take a look at Sam’s Club because I have never been there though my friends told me that’s a good supermarket and worth visiting and buying. But later I was told by the guide standing outside the market “You need to be a member of the Sam’s Club before shopping in it”. Is this sentence natural?

 

[tedmc]

I'd say" You need to be a member of Sam's Club to go in".
I haven't come across a supermarket which is part of a club.

 

[teechar]

Two weeks ago, I was about to take a look at go into a supermarket called Sam’s Club because that I have never been to, there, though my friends had told me (that) ’s it's a good supermarket and worth visiting and shopping in. buying. But later However, I was told by the guide guard standing outside the market “You need to be a member (of the Sam’s Club) to go in". before shopping in it”. Is this sentence natural?

See above.

 

[Skrej]

I haven't come across a supermarket which is part of a club.

Sam's Club and Costco require a yearly membership to be able to shop in them. Such stores deal primarily in bulk volume, so the prices are typically cheaper. The downside is that you have to buy large quantities as well as having a membership to get in the door. Packaging sizes are typically much larger as well - your hand sanitizer for example might come in a gallon jug instead of a six ounce bottle. Those are the two I'm familiar with, but I'm sure there are other such chains.

For the casual or infrequent shopper, they're not always worth the cost of the membership; however if you're purchasing large quantities such as for your business or an institution, then the savings can well pay for the membership several times over. Some people buy in bulk, then repackage into smaller units for storage.

My aunt would buy ground hamburger in 20 lb. rolls, I think it was, then take it home and re-bag it into smaller one lb. packages for freezing and long term storage. She found it cheaper in the long run than buying twenty separate one-pound packages from the local grocery store.