It's easy to get lost in incidental costs and not realize how they add up over time. If you weren't signed up for cryonics, and you inherited $30K, would you be inclined to dump it in to a cryonics fund, or use it someplace else? If the answer is the latter, you probably don't REALLY value cryonics as much as you think - you've bought in to it because the price is spread out and our brains are bad at budgeting small, reoccurring expenses like that.
My argument is pretty much entirely on the "expense" side of things, but I would also point out that you probably want to unpack your expectations from cryonics: Are you assuming you'll live infinite years? Live until the heat death of the universe? Gain an extra 200 years until you die in a situation cryonics can't fix? Gain an extra 50 years until you die of a further age limit?
When I see p(cryonics) = 0.3, I tend to suspect that's leaning more towards the 50-200 year side of things. Straight-up immortal-until-the-universe-ends seems a LOT less likely than a few hundred extra years.
Where'd that $30K figure come from?
You've said you're young and have a good rate on life insurance, so let's assume male (from the name) and 25. Wikipedia suggests you should live until you're 76.
$50/month 12 months/year (76-25 = 51 years) = $30,600.
So, it's less that you're paying $50/month and more that you're committing to pay $30,000 over the course of your life.
What else could you do with that same money?
Portland State University quotes ~$2500/semester for tuition. 3 semesters/year and 4 years/degree ~= $30K. Pretty sure you can get loans and go in to debt for this, so it's still something you could pay off over time. And if you're smart, do community college for the first two years, get a scholarship, etc., you can probably easily knock enough off to make up for interest charges.
I'm not that young--I graduated collect four years ago. If I inherited ~30k, it would go into a generic early start on retirement / early start on hypothetical kids' college fund / maybe downpayment on a condo fund. Given that I'd just be holding on to it in the short-term anyway, putting it in a cryonics fund doesn't actually strike me as completely crazy. Even in that case, though I think I'd get the insurance anyway, so I'd know the inheritance money could be used for anything I needed for when said need arose. Also, I understand that funding through insurance can avoid legal battles over the money.
Background:
On the most recent LessWrong readership survey, I assigned a probability of 0.30 on the cryonics question. I had previously been persuaded to sign up for cryonics by reading the sequences, but this thread and particularly this comment lowered my estimate of the chances of cryonics working considerably. Also relevant from the same thread was ciphergoth's comment:
Based on this, I think there's a substantial chance that there's information out there that would convince me that the folks who dismiss cryonics as pseudoscience are essentially correct, that the right answer to the survey question was epsilon. I've seen what seem like convincing objections to cryonics, and it seems possible that an expanded version of those arguments, with full references and replies to pro-cryonics arguments, would convince me. Or someone could just go to the trouble of showing that a large majority of cryobiologists really do think cryopreserved people are information-theoretically dead.
However, it's not clear to me how well worth my time it is to seek out such information. It seems coming up with decisive information would be hard, especially since e.g. ciphergoth has put a lot of energy into trying to figure out what the experts think about cryonics and come away without a clear answer. And part of the reason I signed up for cryonics in the first place is because it doesn't cost me much: the largest component is the life insurance for funding, only $50 / month.
So I've decided to put a bounty on being persuaded to cancel my cryonics subscription. If no one succeeds in convincing me, it costs me nothing, and if someone does succeed in convincing me the cost is less than the cost of being signed up for cryonics for a year. And yes, I'm aware that providing one-sided financial incentives like this requires me to take the fact that I've done this into account when evaluating anti-cryonics arguments, and apply extra scrutiny to them.
Note that there are several issues that ultimately go in to whether you should sign up for cryonics (the neuroscience / evaluation of current technology, estimate of the probability of a "good" future, various philosophical issues), I anticipate the greatest chance of being persuaded from scientific arguments. In particular, I find questions about personal identity and consciousness of uploads made from preserved brains confusing, but think there are very few people in the world, if any, who are likely to have much chance of getting me un-confused about those issues. The offer is blind to the exact nature of the arguments given, but I mostly foresee being persuaded by the neuroscience arguments.
And of course, I'm happy to listen to people tell me why the anti-cryonics arguments are wrong and I should stay signed up for cryonics. There's just no prize for doing so.