Stack knobs

I have a dual-pickup bass with a 'standard' single volume and tone control arrangement, and I'd like to get better control, without making any permanent modifications. It seems to me that a stack-knob configuration would be the way to go in this regard, but the few places I've looked are CRAZY expensive for the pot + the set of knobs required...is this the situation due to the relatively low demand for the parts inquestion, or am I just looking in the wrong place(s)?

Muchos gracias

I'm looking at $14 for the pot and $13.50 for the knobs, so yeah, they're expensive.
Why? your guess is as good as mine, but they are kinda specialized.
I was going to use one on my Tele with the hummer in the neck, using Allparts 250/500K concentric, then I realized I'd need two. $60 was too much for an impulse purchase, I am still looking for a deal on them though.

http://www.warmoth.com/Concentric-Pot-500k-By-CTS-P720C58.aspx

This is the best deal I've found so far, $25 for the set (pot/top/bottom) and you can mix-n-match the colors for effect.

But yeah, it's a bit steep. If I was talking about my primary instrument I'd be forced to consider it a little more seriously, but for a plaything, it is VERY big deal.