Basically, how much would it take for you to sell out for a year?
2.3x my salary. That's what it took for me to sell out for a year. Well, 9 months in my case.
I took a 9-month term job within my organization in 2010. On my side, I agreed to work ridiculous hours (70 hours a week was the minimum, no full days off), move away from my family, live in a connex can with a roommate, stay confined to a tiny compound, eat really bad food, and potentially get shot at. Their end of the bargain was 2.3x the salary I was making at the time.
Why'd I do it. I had a lot of debt ($21k in cc debt), but that wasn't the primary motivator. I saw it as a path to promotion, and it paid off. After my term was over, I got a promotion with my organization. Came with a huge increase in salary and a move to Hawaii. (Hence, my screen name.)
It was absolutely worth it, but I won't do it again. Not for the reasons you'd think, though. The first time around, it was a path to promotion; now there are other things I need to do (trainings, projects, education, etc), things I need to concentrate on to get to the next level. Simply put, the opportunity costs from doing it the first time were worth it. I don't see the same level of worth in the opportunity costs if I were to do it again, at least, not at this juncture in my career.