The $320 controller has a lot more uses then the $200 one.
Like if you plan on fusing or slumping and want the ability to have it run a programed temp profile. To have it ramp up or down. Rather then just being able to hold at one set point like the $200 model. and its super easy to program and use.
Then there is the
PC linkable model.
That you can hook in a serial port on a windows XP computer and you can use your computer to set your programs and make changes to the controllers settings, Monitor your kiln temps and the ability to record/play back log files of your kiln temps. And is the easiest of all ramping controllers to program threw the PC.
That one is normaly priced at $520.00 But is on sale till after the new year for $420