Beside featuring support for AMD's A-Series APUs these three boards have one PCI-Express x16 slot, two (for the micro ATX units) or four (ATX) DDR3 memory slots, up to six SATA 6.0 Gbps ports, Gigabit Ethernet, no USB 3.0 connectivity, and at least one display output (the A55F-A has three).
This chipset costs less than the AMD A75 but have less features. For example, the AMD A55 FCH lacks integrated USB 3.0 ports, FIS Based Switching, or SATA III 6 GB/s connections. It would still be a good card if you are not interested in USB 3.0 and SATA III.
The ECS A55F-A is the flagship AMD A55 board but all of them are designed for gaming and ECS A55 series supports memory at least 1866 MHz frequency and supports the Dual Graphics functions. There is no word on price yet but the A75 boards retail for as little as €55 so we guess they will be rather cheap.