Are you referring to the standard Pram batteries though that most Macs take, as opposed to the special ones that early compacts take? Those ones are just about affordable if you have one of the particular Macs that won't work without one - as we were saying, the ones for early compacts are ridiculously expensive (especially given that those Macs are not the ones that don't work without a battery). Finding a Mac with a working battery seems very rare - my only find that had one was my 6100, though that died after a few months - even the G3's was dead, and that will have been plugged in for pretty much all of its life and so not draining the battery (though I guess the batteries do go bad with time even if not being used)