Wanna buy a used server?

Dot-coms are dropping from the sky this month like ducks during hunting season. Last week, I mentioned boo.com's shutdown. This week, the Disney-backed toysmart.com shut down. The medical site drkoop.com is widely said to be in dire straits, and even CDnow's ample fan base may not be enough to keep the site spinning.

The list of suspects in this serial cybercide is not short. You could probably blame Alan Greenspan for part of it; the Fed's persistent raising of interest rates over the last several months seems to have finally tamped down markets' voracious appetite for risk. The dot-coms themselves, of course, shoulder significant blame; the number of insupportable business plans backed by bad management floating around continually astonishes me. And venture capitalists play their own part in the merry pageant, putting money into businesses with about as much caution and planning as they would placing chips on a roulette wheel.

I mean, really. A plan like boo's -- selling sportswear in more than 30 countries using a high-bandwidth customized Windows-only interface -- was so spectacularly ambitious that it would have required an iVillage-sized pool of cash and a GE-sized pool of management talent. Instead, the site ran out of money shortly after it launched, and its main backers (big international luxury goods manufacturers) didn't have the fortitude to weather any air pockets.

And it appears that toysmart also grossly underestimated the amount of money required to build the loyal repeat customer base that any retailing operation need to survive.

I recently pulled down some numbers on e-tailers that are so revealing that they shouldn't be relegated to the Win Letter numbers. The Boston Consulting Group found that e-tailers spent $82 last year to win a new customer. Offline companies spent $12. E-tailers spent 119 percent of their revenues on marketing. (No, that's not a typo.) Only 27 percent of the typical e-tailer's customers are repeats. The figure is 34 percent for stores. So stores spent one-sixth of what dot-coms spend to attract customers, and more of the store's customers come back.

From those figures, it looks like this week's pain is just the start.