Island hopping rates usually depend on the package — for Hundred Islands, the standard boat rental starts at around PHP 600–800 for a small group, plus the entrance fee to the national park itself. What you get depends on which islands you want to visit — Governor's Island, Quezon Island, and Children's Island are the most popular, each with something different to offer.
I've been meaning to go back since my last visit years ago. Masaya talaga ang island hopping doon — each island talaga may kanya-kanyang vibe, iba-iba ang rock formations at yung view from the top ng ilan sa kanila is worth the climb. What month are you planning to visit? Summer months (March to May) can get crowded but the water is at its clearest. Has anyone here gone recently? Curious how the facilities have improved.