Now Gentlemen....Play nice (and I don't want to hear who started it) ....Ernie; I believe you have a plane to catch? I'm hoping to read about your days meandering San Pedro for a month.

Jeff - people are being nice - but I would suggest you drop the word 'CHEAP."
I checked your profile which is empty so tells me nothing about where you are from or what you are accustomed to.
We are a small country but little distances equate to a long way off. Glover’s reef is to Ambergris Caye as New York City is to Los Angeles.
From Amb.Caye or Caye Caulker there are boats to Turneff and Lighthouse Atolls. They are not cheap - not even inexpensive and I find that those that go pretty much all charge the same. The same goes for reef diving. If you sign up with a shop and do at least 5 days of two tank diving and maybe even a night dive you might get a discount. The old saying "you get what you pay for" really applies here. I live here and would not put my life in the hands of a cut-rate/cut-throat operation.

That said, even I cannot book a trip for whale sharks. There are only a handful of operators who are allowed to take people OUT - and I mean WAY OUT to TRY and see whale sharks. And of these only a limited number of boats are allowed to go on any given day.

For you I would urge you to come to one of our island and stay at one of the hostels - and yes - book ahead of time. Once here you can figure out the diving. Just be prepared to pay - remember - gas is very expensive here and all diving is done from motorized boats.
I remember when I dove in Hawaii that two tank dives cost $100 US and that was 20 years ago.
You could make points by filling in your profile.

Caye Caulker diving - definitely Belize Diving Services, they don't just stick to local diving (though sites around sp and cc locally are awesome) - they have several boats and do run out to both blue hole, turneffe north and south and also out to Lighthouse reef without the blue hole. I have worked on the Sundancer and yes the sites they go out to are fabulous and you are pretty much without fail going to be the first dive boat out there, the boat is fabulous and service second to none. I worked there with Anne Marie McNeill who now owns Avadon Divers in Placencia (won the 2011 Belize Tourism Board's award for "Best Tour Operator of the Year,") - your best bet for going to Glover's to see whalesharks.

here are some contacts:
Chip or Dani Petersen at Belize Diving Services, Caye Caulker
Anne Marie & Phillip McNeill at Avadon Divers Placencia

and I agree with the other posters regarding "cheap" - it's a competitive business here and if one shop is cheaper than the others then ask yourself "what has been compromised?"..... would you go for the "cheapest" skydiving outfit in a competitive market???

cut rate chutes...only used once