One of the newer TI microcontrollers with ARM Cortex M4F is going to be in the market soon. It is offered in a relatively low price.
Best of all it contains a Floating Point Unit, so you know what you can do now. 1.234 x 5.678 with much lesser cycles!
However the things are only be shipped to me by late September, so need to wait for me to find a suitable compiler (a no-cost GCC) and write up some guides on how to play with it.
Texas Instruments Stellaris Launchpad