In this study, we estimated the cost of implementing the Self-Determined Learning Model of Instruction (SDLMI), an evidence-based practice in secondary transition, at scale in 17 U.S. school districts to enhance self-determination and transition goal attainment outcomes among 340 transition-age adolescents with intellectual disability. An advantage of the SDLMI is that it can be overlaid upon any curriculum and, therefore, can minimize opportunity costs for self-determination instruction. Using the ingredients method, the current study: (a) identified and described the essential ingredients of SDLMI implementation in typical high school settings, (b) assigned and described the cost of needed ingredients, and (c) calculated a generalizable estimate of the average cost of using the SDLMI with 340 students for one school year across 17 school districts to be $40,221.26 (or $118.30 per student). We discuss how decision-makers considering using the SDLMI in their context can minimize costs while maximizing effects on transition goal attainment outcomes. Several implications of these findings for the field of transition are also described.