POLAR do a good range of heart rate monitors . To be honest unless your looking into racing serioulsy you really dont need a hrm,a stop watch will be fine,just to note your progress really.
For a beginer and/or fun runner there no need to be doing session at a percentage of hr or building lactic thresholds,just getting out 3 times a week and enjoying it will do you the world of good,maybe then it'll lead onto thinking more serioulsy about actually racing as opposed to running a certain event.