How much does a cam belt cost on a 2004 Honda CR-V?

I think you are actually asking what it costs to REPLACE the timing belt. The cost of the belt itself is not the big expense. The labor to partially disassemble the front of the engine and get to it is where the expense comes in. The cost of labor and materials vary too much around the country to make any estimate other than to say it's going to cost you several hundreds of dollars. The best thing to do would be to contact your local Honda dealer and ask.