Do not use dollars per story point in building financial baselines or efficiency metrics. There is a danger that these metrics will be used for financial planning and for comparing projects, which is quite dangerous.

Velocity changes over the course of a project (due to learning curve, requirements clarity, etc.). Generally, the number of points for an item (as a relative measure) should not change (unless the scope does) but the velocity of points completed per sprint should change frequently up and down throughout the project due to technical innovation, the need for coaching new team members, and many other factors. Also, the size of a point should be relatively consistent within a project, but varies greatly across projects. Remember: a simple requirement is rated a "1" and then the others are all compared to that one to determine their complexity. What is a simple requirement in one project will be very different from what is a relatively simple requirement in a different project.

The agile community HIGHLY recommends not using dollars per point for any purpose.