George K. Cunningham and J. E. Stone, JAM Press
This essay from a forthcoming book (Value Added Models in Education: Theory and Applications, edited by Robert Lissitz) concludes that "the achievement gains associated with NBPTS certification are small and thus give rise to the question of whether its costs are worth its benefits." As a lower-cost alternative, the authors recommend value-added analysis of student test data by teacher. In particular, they suggest monetary awards or bonuses to teachers whose pupils "meet or exceed the 90th percentile of local district gains." What this mostly is, however, is an analysis of four extant studies (all small) of NBPTS certification, one of them by co-author Stone. You can find it here.