Some deals only come around once or twice a year, but offer savings that justify the wait. This post is part of our series on such 'don't miss' sales.

Stonehenge. Scooby-Doo cartoons. The Manolo Blahnik Sample Shoe Sale. To some degree, these are all mysteries, but it is Manolo Blahnik that is the least explainable enigma of them all.

After all, we know where to go to visit Stonehenge, and in a Scooby-Doo cartoon, you usually have odds going that it's one of two or three people the gang have previously met in the last 20 minutes. But exactly when is a Manolo Blahnik shoe sale? Good luck finding that out. You'd be better off trying to learn the nuclear code in the president's briefcase.

Actually, you can find out, but the sale is never announced until just a few days before the event, and there's little rhyme or reason to the dates, at least from the point of view of anyone who doesn't work in the inner sanctum of the Manolo Blahnik account office. Usually, you can count on the sales being on any given day in May and November, but Manolo Blahnik enjoys keeping the shoes' fans on their toes. For instance, in 2004, they had a sale in the month of February; earlier this year, they had one in January.

The mystery and suspense works, and so does the exclusivity. If you want to be among the first shoppers, you have to be invited to the sale, which happens if you know the right people or if you buy a lot of Manolo Blahniks and thus get an invitation. After a few hours, then the general public is allowed in.

When the shoppers get there, hoping to get $500 shoes for, say, $100, they shove, push and practically climb all over each other to get to the shoes, which are sold at the Warwick Hotel in Manhattan (they're only sold there and at the Wynn Las Vegas casino and scattered boutiques around the world). Celebrities swoon over them. Princess Diana liked them. Madonna supposedly once said that wearing his shoes was "better than sex." And in the fictional world, Carrie Bradshaw in Sex and the City was obsessed with Manolos. On the Internet, shoe blogs are consumed with them.

And why not? There's an air of mystery, mystique, celebrity and it even taps into the raw psyche of the shopper. After all, when you come to this sale, you can't bring your credit card or pay with a check. You have to bring cash. Even visiting Stonehenge isn't this complicated. But it works. The lines of shoppers stretch for blocks and blocks.