The meta-uncertain excuse doesn't make a lot of sense to me- it's enough that you want enough expected gain to justify the transaction cost.
Or is there some kind of rigorous notion of meta-uncertainty you're appealing to?
Hmm. Actually, it's because I haven't bothered to collect all the information I could, and so my bid-ask spread serves as a confidence interval. If it were too small, then I'd actually find it probable that someone else could do the research I haven't, figure out that the true value is on one side or the other of my interval, and exploit me.
As we did last year, use this thread to make predictions for the next year and next decade, with probabilities attached when practical.
Happy New Year, Less Wrong!