By that reasoning we should expect higher traffic to thirtysevensignals.com than 37signals.com. Having a numeral in your domain seems unwise but for a location oriented company "20" is a winner. It is not worth $70k though IMHO.

Aday.com is worth thousands. I've been looking at hundreds of potential domains for a daily deal site and it's been frustrating. If I had found aday.com for $10 I would have shouted so loud all my neighbors would be deaf.