Best Programmers make the difference

Reading Joel's "Hitting the High Notes" points out how stars make a difference in movies and they are paid accordingly. And Joel argues that best programmers are similar:

Here's why: duplication of software is free. That means that the cost of programmers is spread out over all the copies of the software you sell. With software, you can improve quality without adding to the incremental cost of each unit sold.

Essentially, design adds value faster than it adds cost.

Or, roughly speaking, if you try to skimp on programmers, you'll make crappy software, and you won't even save that much money.

I personally would argue that the best programmers are artists and most programmers are craftsmen. I don't know how people -- let alone companies -- can weed out artists from craftsmen. One can test for basic competency of a craftsman but then how to weed out the best from the common? And if you're one of the better programmers, how can you assert your abilities?