Many brands do sell 4 channel chargers. I think the Dinamite Prophet sport Quatro does meet the best requirements with all connections to the front so it is easy to place many in line.

If you vant t save money with an easy charger you can also think of getting a bunch of SkyRC E4 chargers.

And thinking much cheaper, get some 30 dollar Server PSU's (12v-60A) and a bunch of Turnigy B6 chargers (or the smaller B4 version)
http://www.hobbyking.com/hobbyking/s...6S_Lipoly.html