Cost to "apply" varies depending on the number or programs. It's about $100 for the first 10 programs, then I think ~$8 per program after that up to 20, then ~$6 per program after that up to . . . It keeps going. I'm assuming you only mean cost to submit the application on ERAS. Registering for the Match, traveling for interviews, etc brings on a whole other set of expenses. Anyway, ERAS charges by total number of programs, it doesn't matter if some are prelim and others something else.