Can I adjust varistor range?
An easy trick is to place a fixed resistor, say 10 kOhm, in parallel with the varistor. The total resistance will now vary between 0 and 9.5 kOhm. But the problem here is that the total resistance does not vary linearly with the varistor's resistance, f.i. when the varistor is at one quarter, at 50 kOhm, my circuit will still be at 8.3 kOhm rather than 2.5 kOhm.

If you do need linearity you'll need other, more complicated components (I'm sure that with an opamp you can simulate this).

The bigger question is though, in what circuit do you want to use this? Maybe there's an easier way to accomplish this.

(You could also place 20 of your 0-200 kOhm varistors in parallel, which also gives you 0-10 kOhm, but that doesn't seem like a very good solution to me either...)