Depends on the climate of the room your tank is in. If you tank reaches up in the 85 range you may consider it. Most people have heaters, because temps are commonly from 70-75 and a lot of people like to keep their water around 78ish. Also, temps drop at night, and a heater will maintain the temp.
Advice, monitor your temps throughout the day and see how high it goes before spending $800+ on a chiller.