Thanks for the comments!
I have obtained special batteries from these people... they appear to be new and fresh... but very expensive:
http://www.batterymart.com/c-industr...dy_504_battery
Most of the time, I "fake it" using cheap 12V smoke alarm batteries, such as the Energizer A-23 , or stacks of watch batteries. Sometimes I just "go without" as most ranges (except the highest ohm) will function fine without the expensive battery.
Not affiliated with the battery vendor,
jr