My year of wine

Wine prices can shock. Take the price of the 1997 Petrus Pomerol, for example. At the Saxon Hotel in Johannesburg it costs R55000 for a bottle of what wasn't a great vintage.

The most expensive bottle of wine ever is a 1787 Chateau Lafite that sold for $156450 in 1985. The reason: That bottle once belonged to America's founding father, Thomas Jefferson. But Petrus? It's a Merlot, for goodness sake. Remember what Miles in the 2004 film Sideways said? ''If anyone orders Merlot, I'm leaving."

I've been told by rich friends that journalists don't always understand the worlds they write about. Without drinking the expensive stuff, I'll try.

There is the law of demand and supply. As more people become interested in drinking luxury wine, the prices go up. The supply of the better quality old world wine doesn't. The Petrus vineyard in Bordeaux, for instance, is only 11.4ha.

The grapes are hand-harvested over two or three days, and 2500 cases of wine are made a year.

Thelema Wine Estate in Stellenbosch, by comparison, produces 40000 cases. Other costs that push up prices are oak barrels, French more expensive than American; the time taken to age the wine; and the terroir. It's more expensive to harvest grapes growing on steep slopes than those growing on flat plains.

But will I get bang for my buck? No. More expensive wines are often rated higher on taste than cheaper ones, but only if tasters know the prices beforehand. Stephen Dubner, co-author of Freakonomics, said blind tastings repeatedly prove that wine critics can't distinguish between a $15 and a $50 bottle of wine.

Back to Sideways. There was a reason for Miles to dis Merlot. The film's producers had originally wanted to use a Petrus as Miles's treasure bottle. The wine estate's Jean-Pierre Moueix rejected the request, saying: ''I found the script unexciting and declined."