You're dreaming if you think Craigslist is three guys in a garage. They have ~30 employees, and I can guarantee that they have large server, colo and bandwidth costs. They also make their money off of direct payments (as opposed to advertising), and their annual revenue is around $100 million, by the estimates I've seen. So they're profitable, but not hugely so. (By way of comparison, Netflix makes a bit over $20 million net per quarter, on over $300 million gross per quarter.)

I'll grant you that they're exceptionally small for a website of their size -- but being "exceptional" means only that they're the exception to the rule. The rule is what's important.

Actually, they are quite exceptional. Craigslist gets more traffic than either Amazon or Ebay and those companies respectively have 16,000 and 20,000 employees.

You've missed the point: Craigslist is so far and away the exception to the rule, it's practically non-reproducible. And for what it's worth, they're also not nearly as profitable as either Amazon or EBay, regardless of their traffic.

There's simply nothing about Craigslist that you can count on reproducing. If you're creating an internet company today, and you're aiming for hundreds of millions in revenue, it's 99% probable that you will need to spend more money than they do.

The thing that is reproducible about Craigslist is their simple, functional layout and organic, community-centric growth. Much like HN.

Well, of course you can reproduce their design. But reproducing their design won't reproduce their success. If it were that simple, every website would look like Craigslist.

Again: you're missing the point. Craigslist is the exception to the rule. It's a product of its time. For any value of X, if you tried to say "this is the way Craigslist did X, therefore I should too," you'd very likely be wrong. And in any case, Craiglist is pretty far from the romantic notion of three guys in a garage. It's an expensive site to run, even if it's more cheaply run than other big sites.