For the costing concern here's the rough estimate (DIY):
Bus from south bound terminal to oslob - P125 to P175/pax (sorry I forgot the exact amount) same amount going back to south bound terminal to oslob.
Then the P610/pax for the whale shark encounter.
Total cost of P785/pax. This was within out budget of around P1,500. Very well within the budget. :-)