By extrapolation writes are IO bound you don't need crazy expensive things to get to the needed number of IOPS Intel 750 is 230,000 random writes @ $320 per PCI-E SSD. 9 drive
config is over 2,000,000 IOPS for less than 3K.
Yeah it's a bit more complex than that... The disk "IOPS" number on the box doesn't translate 1:1 or even linearly to number of committed durable transactions per second. You should try this with postgres and see how it goes.