My charger is cheap and simple, but is for the lower voltage requirements of LiFePO4. I use some cheap (search eBay) DC DC converters. They have isolated inputs and outputs, so can be connected to a common power supply and still hook up via a multipole connector to the battery pack.
I'm intrigued by this idea for charging multiple LiFePO4 cells, and I think I have found some of these on eBay (although they are a little more expensive than when you bought yours). They specify 48V/2A input, so I assume this will be the current demand during the early phases of charging? This being the case, I guess I would need a pretty hefty PSU to drive more than 3 or 4 of them?