DEMO9S08QG8 seems in fact to fit your description: its uCU may be extracted from the Demoboard and equip an external breadboard. 9S08QG8 is a cheap 3.3V 16pin low-end uCU.
Please consider that most Demoboards may also use their internal BDM port to program virgin or flashed uCU of the same series on external breadboard or PCB: this is quite the same than to use the uCU on the Demoboard, considered that the cost of this kind of device is 1 to 2$ for a new blank part.
I would chose DEMO9S08SH8 which can program either 9S08SH and -SQ part in the 20pin DIP inside or of any pinning size externally. This part is a 3.3-5V device and is more powerful and versatile than a 9S08QG8 and one of the few still available in the DIL size (20pin).