The easiest and cheapest way is simply to take the ferry from Coz to Playa (about an hour), a taxi to the ADO bus station, then an ADO bus(4 hours 15 min)to Chetumal, then Novelo's bus to Corozal, and from there either fly (four or five non-stop flights a day on both Maya Island and Tropic Air) to San Pedro, or take the daily Thunderbolt ferry.
The whole trip will cost less than US$75 even if you fly from Coro.
Belize books and publications by Lan Sluder:
Belize First Magazine (http://www.belizefirst.com
Fodor's Belize & Guatemala Guide (new 4th edition coming this fall)
Adapter Kit: Belize (the first and only comprehensive guide to living, retiring, working and investing in Belize -- a best-seller on Amazon.com)
San Pedro Cool (the first and only visitor guide to Ambergris Caye)
Belize First Guide to Mainland Belize -- sold out, new edition coming early 2003
UpClose Central America
Belize Book of Lists -- sold out, new edition coming early 2003
Best Hotels of Belize -- coming late 2002