Thatch and wood fire redardant costs about $60-$80us per gallon in the states. It's not worth it if it is for a house, since everything else in your house will burn. The exterior conditions in Belize will nulify a coating in about a year. I have seen plenty of house burn down that had "treated" wood shake roofs.
Proper fire prevention and a couple of fire extinguishers will work better. pm me if you have a specific question about what you want to apply it to.