There has been a bit of hand-wringing in the media in the last few months over same-store sales. This hasn't been without reason, as same-store sales have been worsening and both Sears Holdings (NASDAQ:SHLD) and Home Depot (NYSE:HD) recently warned that their comps would be weaker than expected.

But there are still retailers with pockets of strength. Among them is Motley Fool Stock Advisor selection Costco (NASDAQ:COST). This could be because the average Costco member earns more than the average consumer, or it could be because Costco's model retains its attractiveness for consumers longer than other models. I think it's a combination of the two, but I'll let you decide for yourself.

In June, Costco saw its same-store sales climb 6% overall, with a 5% increase at U.S. stores and a 10% increase at international locations. Across the U.S., Costco saw the strongest increases in the Midwest, Northwest, Northeast, and Texas. Internationally, Korea and Taiwan retained the strongest local currency results, and the company did see a boost from the strengthening in the English pound.

Competitively, there was a different look this month. In the last few months, Costco has easily bested BJ's Wholesale (NYSE:BJ) and Sam's Club, which is owned by Wal-Mart (NYSE:WMT). This month, however, Sam's Club came out on top with a 9.6% increase, and BJ's is not far off from Costco with a 5.3% increase in same-store sales. BJ's has a larger focus on food and groceries, so it is possible that the Independence Day holiday helped results, but this is only one month of results, which makes it tough to read too much into it. It is interesting to see so much strength across the warehouse sector, though, at a time when so many other retailers are struggling.

Costco continues to be an attractive company that I think is fairly valued. If the markets hiccup at all during the second half of the year and Costco suffers, it would be high up on my list of positions to add to at around $50. Hopefully I'll get that chance.

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Nathan Parmelee has owned shares of Costco for years, and shopped there for a bit longer. He has no ownership stake in any of the other companies mentioned. Home Depot and Wal-Mart are Motley Fool Inside Value selections. The Motley Fool has an ironclad disclosure policy.