Hi @Mark_Grass
I'm looking at the NUCLEO-F411RE board. The mbed solution looks pretty nice. $10.33 100Mhz w/FPU etc.
Several of us are hoping to port the current STM32F103 Arduino code to STM32F4xx
I have a 407VGT (168Mhz) Discovery board and Alexey (@hiddenPilot) also has some from of STM32F4 Discovery board.
If you are interested in helping get F4 to work, join us on the thread in the micro controllers section. The More the merrier 