I have been asked about the entrance fees to the National Parks. The fee is $7 per person.
However, if you are a student and carry a student ID card, ask at the entrance gate for a possible discounted student entrance fee.
Also you may ask for a senior discount, showing your passport-however; at this time I am not aware of any senior discounts.
Multiple entrance passes (sold at discount)? The office of Costa Rica Tourism ICT (located downtown San Jose) may offer this. But, getting down town to obtain it is probably not worth the time and expense. San Jose is a very crowded city and traffic jams are common.