Shopbot stuff is a bit pricey in general, but a decent ATC router spindle is going to be in the range $4 to 5K for a 2.2KW. They are different than a mill spindle in that the motor is integrated into the spindle assembly. Then you have to add a tool turret, or use a stationary tool holder. There is some cost for the software to run it all, but that is pretty much a one time cost for the manufacturer, and thus becomes a nice profit center for them.
Yes, Tormach uses a collet with their TTS tool holder system which works with their power drawbar and requires no modification to the system to use with a tool changer. The BT30 system uses a pull stud system on router spindles and all of the puller hardware is integrated into the spindle assembly.
You are trying to compare apples and oranges here.