TRC will reimburse you for reasonable expenses incurred during writing the rallye (e.g., mileage for running the route and for precheckers). As of 2010, TRC again reimburses food and nonalcoholic drink for RM(s) and rallye workers, up to the limit of $1 per competing car.
If you are planning on spending more than $20 on various giveaways, etc., you need to run that by the board first. (Note that we currently get about 20 cars, so we plan for 30 cars. That's what the printing instructions are. Therefore, $20 is only $.67 per car.) The board may have some interesting resources and ideas that might get the same effect in a more cost-effective manner.
See Printing for TRC Rallyes for current printing reimbursement rates.