I have been using Reefkeeper Lite from Digital Aquatics. The cheapest config ($100 - 120 price range) come with controller unit, one temp probe and a 4 outlet (controlled) power bar. I love it. Plug the heater into power bar, program Reefkeeper to turn on that plug when Temp (from supplied probe) drops below 'X' value. I bought the base package and an extra power bar and am using to control lighting, heaters, sump pump, skimmer and power heads (has a wave feature). You can add other modules & probes for things like PH, salinity, orp, float switches etc., but Reefkeeper Lite is limited to 4 modules (1 power bar = 1 module), they have an Elite version if you need more. Web site for them is www.digitalaquatics.com.
Darrell