For solo tourists visiting Saipan for a short time, is there a cheaper way to dive than going through a dive shop? I'll probably just pony up the money, but the prices are awfully expensive considering it is Saipan--diving prices in the Philippines are half. I read that you can get tank fills for $4 or $5, but I don't know any of the dives sites and I don't want to dive alone--conundrum. Hope the diving's worth it.