Malaria Tablets (Dar es Salaam)

Hello! I'm moving to Dar es Salaam in August (for at least 2 years) and I'm wanting to find out about malaria tablets. Today I was prescribed a 3 month course of tablets for almost £300 which seemed very hefty (especially since I'm going to be living in Dar for a while)! Is it possible/easier/cheaper to buy malaria tablets once I'm in Dar? Do most expats use tablets daily or not bother? Has anyone got any ideas for cheaper options? Is it a good idea to 'risk' it and not bother taking malaria tablets. Any advice would be much appreciated :) :)