Where to Find 4K Potentiometer, 1/4 Turn, for Electric Organ Keyboard Balance in Mexico?

Hi everybody!

This regulates the balance between an electric-organ's 2 keyboards, say upper keyboard vs lower keyboard.

I haven't found anything like that at semiconductor-stores (I live in Mexico). http://1drv.ms/1d6Oa1J

I'd appreciate your oppinions. I'm open to any suppliers or ideas.