I've been a contractor on and off for years (and I still do it on the side...$100/hr for Linux kernel/driver and systems programming with emphasis on digital video ). I know why you charge more as an IC.

$120/hr is on the high side of what I've seen fellow ICs make in this town. $120k/yr is on the low side of what I've seen senior devs make in this town. 2x is suprising.