From The Economist on the software industry:
An industry rule of thumb is that a bug which costs $1 to fix on the programmer’s desktop costs $100 to fix once it is incorporated into a build, and thousands of dollars if it is identified only after the software has been deployed in the field.
The larger idea about fixing things early in its lifecycle is interesting. Take hiring/firing. We almost always wait too long to fire someone. When was the last time you heard someone say, "I think I fired him too soon." The longer we wait to correct a screw-up, the more expensive the mistake becomes. Yet stubbornness or overvaluing sunk costs often keep us from acting as quickly as we should.
(Here’s my Rule of Thumb wiki.)