Last 2 trips I used Omero Graniel for $200 US. he took us fishing snorkeling & a beach Bar-B-Que, he brought 6 lobster with him, cooked the fish, lobster & potatoes in about 15 min. and it was one of the best meals we had.
e-mail MGRANIEL@HOTMAIL.COM Tel:226-2729 625-7631

I would also reccomend a half day trip over to Caye Caulker.
Take a cart across the bridge North & stop at the Palapa Bar, then down to the next dock & my new favorite place Akbol, great beach Bar with pool & killer view & awesome cheap food.