Quote from Remiraz:
I think min. account size is $2k. (check out www.interactivebrokers.com)
If you do 250,000 units per lot you might get a better deal on commissions than FX Futures. Otherwise, the comms is much higher than futures for standard 100k lots. If you're doing less than 100k lots, you're better off with a spot fx dealer like Oanda or GFT.
Thanks remirez