I reserve some uncertainty that I'm fundamentally wrong about how physics and anthropics work, so I'd treat the question the same as "how much money would I have to pay you to accept a ~10% chance of instant painless death"?
In other words, $20 definitely ain't going to cut it, but a hundred million would. (I have a hard time estimating exactly where the cutoff point would be.)
When I've brought up cryonics on LessWrong [1][2], most commenters have said I'm being too pessimistic. When I brought it up yesterday at the Cambridge MA meetup, most people thought I was too optimistic. (I think it could work, but there are enough things that could go wrong that it's ~1000:1 against.) What makes the groups so different on this?
[1] Brain Preservation
[2] How Likely is Cryonics to Work