I'll jot some down here... When independent consulting... There is a rule of 3.
If you feel your time is worth $50 per hour, your billing rate is $150.
why?
1/3 to you
1/3 to the lean times between gigs
1/3 to the tax man
If you are working at fixing this sort of thing, you should be expecting closer to $100 per hour to you.
Trust me, they can pay a $300/hr billing rate without concern in most cases.