Oh I wouldn't even entertain a contract position...

I had this while back...I was working for company doing DR/Replication scripting...I was about 2/3 way through the job and they decided that "they could finish the job themselves" and graciously released me from my contract...

They called me back about 2 weeks later, at which point I quoted them 400% of my original rate, payable in advance, to finish the work. ;-) They were fucking LIVID..

Of course, they didn't re-book me, but the rumor mill told me that they brought it in about a year behind schedule and at about 2x the budget they had allocated...

Helpful hint - do documentation LAST. If they fire you before it's done, they get SQUAT. I didn't even have passwords written down for them.

Generally consultants on short-medium length contracts cost 3-5x hourly rate of FTEs, for long-term contracts it's usually around 2x, at least in the industries I've worked in. You'd be low balling yourself by only asking for a 50% increase for contract work.