I am planning of doing my own tour as I am traveling w/5 & ship tours can be very expensive. I am visiting Altun Ha ruins & Belize Zoo for less than 1/3 the cost of ship tours. All of the tour guides are required to be registered with the Belize Tourism Board. You can go to their website at www.travelbelize.org
then click on tour services. Click on what you want to do & they will give you a list of registered tour guides along with their emails to contact them directly. I sent all that I got the same email of what I wanted to do and got quotes before I pick my guide. Good Luck!