AF 500 FTZ Power supply

To cut a long story short, i now own 2 AF500 FTZ's one with an intact hot shoe and one with a broken one. I'm looking at using both of them (one a slave) in some 'home studio' style shoots. My issue is that i'm going to truck through batteries like nobody's business so, i'm looking at constructing a power supply for it. Has anyone else done so?

Not constructed a battery pack yet but why not stock up rechargeables at least first.
I run the Hybrids and they do give quite a good term without costing the earth.

Alan