7 Surprising Things You Can Buy at Costco

NEW YORK (TheStreet) -- Costco Wholesale (COST) revealed its most expensive bargain yet this week -- a $1 million diamond ring.

There's only one of these 6.77-carat rings, which is actually discounted from its $1.6 million value.

The wholesaler has been selling engagement rings and high-end jewelry for several years, having already offered diamond in the $200,000 to $300,000 range. But this is the most expensive item to date.

While Costco is best known for its cheap bulk basics and discount electronics, next to the 80-packs of toilet paper, 30-pounds of pasta and giant televisions you can find some surprising buys.

Costco, while lumped in the discount sector along with rivals BJ's Wholesale(BJ), Wal-Mart(WMT) and Target(TGT), actually claims to cater to a high-end shopper, noting that the average income per household for its demographic is about $100,000.

This could be why Costco has been outperforming its peers, reporting a 13% surge in same-store sales in March, topping analysts' estimates of 7.4%.

In comparison, BJ's posted a 5.3% increase, while Target actually saw its comparable sales fall 5.5%. Wal-Mart, which abandoned the practice of reporting monthly same-store sales data, has seen its U.S. sales decline for seven consecutive quarters.

Costco has demonstrated strong traffic and membership trends, while gross margin improves. And while some of its unique offerings aren't the only, or even biggest, reason for its success, they certainly play a part.

Here, then, is a look at some of the other unexpected buys you can find at Costco....