Determining the theoretical 'worth' of a programmer is difficult because demand for programmers is typically tied up with a firm determining how much value they can get from a particular hire. Where information regarding the value of a skill is difficult to quantify due to the largely tacit nature of the skill, valuation is difficult.
It is, however, possible to examine value by examining the differences in demand. If a firm compares their programming staff to a theoretical programmer, then determine what they would be willing to pay for wrt some specific added value that they would get at a particular level of execution, they can effectively price talent.
The take home point is that your first step to pricing is by way of comparing delivered value. The interesting part here is that programmers will likely discover that their skillsets are highly asymmetric wrt value delivery.
My question is how do we measure delivered value? Seems the push for quantifying contributions (https://news.ycombinator.com/item?id=5462622) might be related to the difficulty in value calculation.