Much easier to have wax in the heater than to keep getting up and microwaving. I live a fair drive from a beautician so getting there is not always possible. Next best thing is do it at home. I generally microwave the wax for a minute or 2 and then pop it into the heater. I dont have to get up and microwave again as it keeps it perfect. I have only ever bought the waxaway wax for it but I am assuming you can probably use other cheaper wax. They also have the roller cartridge which I am considering buying so it wont be so messy. I tend to drip wax all over the place when waxing. If you are wanting to do home waxing it is well worth buying a heater.
Keeps wax at a great temp
Slow to melt the wax