I was looking for studio flashes a couple years ago and fine combing ebay for affordable yet sturdy reliable units, I also wanted to be able to drag them out to locations beyond the comforts of accessible power outlets. So that would be something a good bit outside my reach. A big waste of time. If it had not been for a polish guy with an ebay shop and a webshop called fototip.pl.
They have a brand called Quantuum that produces very sturdy aluminium studio flashes, very good specs. And they have a little four pin socket on the belly that connects to a battery pack. Reload times are a couple seconds on full and instant for less than half.
I paid £300 for the 300WS unit with battery and a 70cm Beauty Dish.