“Buying a car with the hood welded shut”
In Open Source and You, Ron Goldman points out:
No one would buy a car with the hood welded shut, but that is essentially what commercial software is.
I’ve never thought about it quite like that before, but that would be about right. 
The rest of the article is well worth the read if you want a non-techie explanation of open source software and its value.
Via Steve Lee on the oats-sig list.