It takes a unique business to sell a diamond necklace or ring for more than $200,000 a pop, but also move toilet paper, soda, and other essentials in volumes that makes your head spin. But that's what Motley Fool Stock Advisor selection Costco (NASDAQ:COST) does -- and does frighteningly well.

The details the company has provided thus far are in our Fool by Numbers published earlier today. The company does not provide a balance sheet or statement of cash flows with its results, but it generally posts them to its website within a day or two.

One item not in our Fool by Numbers is store openings. Normally, I don't pay close attention to store openings, but Costco intentionally ramped up its openings this year to a target of 28. Through the first three quarters, the company has opened 16 new warehouse clubs, and it plans to open another 11 or 12 in the fourth quarter (with one being a relocation). This is considerably more than the 16 to 23 stores a year the company had opened the last few years, and Costco believes it can gradually increase its openings in future years.

On the company's conference call, one of the analysts asked how inflation has affected Costco's performance. It's a logical question, given that Wal-Mart (NYSE:WMT) pointed toward inflation when it released its comparable-store sales last weekend. It's also a question that comes up on Costco conference calls on a fairly regular basis, and the answer doesn't change much. The company is seeing inflation in gasoline (obviously) and in some food items. However, the deflation the company sees in large televisions and other electronic items nets out most of the inflation it sees. That was the answer a few quarters ago when I last heard the question asked, but inflation's presence in food items and perishables is something to keep an eye on from a broad economic sense.

The other item that stood out to me was the company's patience. Costco has opened a few Costco Home stores, and it's experimenting with some other items, but it has no plans to start rolling any of these experiments out at this point. In some cases, the experimenting and studying is going on over a fairly long period. The company has had its first Costco Home open for about two years now, and it's still taking its time and making sure the concept is consistently profitable. This may seem slow on the surface, but when you consider the capital involved in opening a store in a different format, it makes a lot of sense to take the time to analyze the concept inside and out.

While I don't think Costco's shares are a great value at current prices, I don't consider them expensive, either. Generally, these judgments are made on the basis of the company's P/E in comparison to Wal-Mart and BJ's Wholesale (NYSE:BJ). Relative valuation is a logical tool to use in many types of analysis, but in the case of Costco, and Wal-Mart to an extent as well, I think looking at the P/E in isolation is a mistake. In doing so, you are likely to miss the true cash flow generation of the company, and what it would take in investment to duplicate what Costco does. To me, that's a very large part of the company's competitive advantage -- and what should allow it to maintain its healthy return on invested capital.

Wal-Mart is a Motley Fool Inside Value recommendation.

Nathan Parmelee owns shares in Costco, but has no financial interest in any of the other companies mentioned. The Motley Fool has an ironclad disclosure policy.