Hey, FIRST already sorta answered this question for you in a paper they published, it covers the cost of everything for a typical team (and you can customize it for your own needs) You will find this useful information on pages 41-42 (Appendix A) of the
FRC Handbook.
Bonus tip, if you haven't yet, read the
FRC Handbook, they put a lot of work into it and it can answer a lot of questions.