I usually get the 200watt ones and they are about $40 or a bit less. I'd check out amazon.com and price them. You want the wattage to be enough to heat the water and not have to be on all the time to keep the temp, thats why the 200w should be good.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.