Thanks for the official counts, I appreciate the data!
The rarity questions you're asking, I think you're driving at the Universal Rarity Scale:
http://3tend.com/article/coin-grading-basicsThere won't be any way to know the precise numbers without hindsight. Factors, in my mind, will include:
-The 'curb appeal' of the coin - how does it make you feel when you get that first look?
-Historical significance, the story behind it.
-Rarity (with guaranteed future rarity).
Keeping with my horrible bias, I of course think Casascius coins win in all regards. They were the first minted digital currency, the first Bitcoin. On top of that, we get a misprint - the collector gods have smiled upon us :-)
Observing what the market has looked like over the last year, I have seen:
-Even a few months ago, you could find multiple 1 BTC error coins up for sale at any given time. Prices generally varied from 3 to 6 bitcoins for the 1 BTC error.
-Prices seemed to hit a cap. Then, rather then seeing them go up or down more, supply dried up.
I suspect that many of the original buyers do not have intentions to resell them, certainly not for a 2x or 3x profit. In short, at the present moment, I don't feel the market appreciates the true value of Bitcoins. There is 'nobody' left to sell (because current prices are too low), and no one left to buy.
A final note on rarities. It's good to keep in mind that to compare apples to apples, you need to subdivide the populations you got into grades.
VERY crudely speaking, I would estimate:
1 BTC w/ error: 5098
Lost: 1500
Heavily worn: 1500 (Graded between maybe VF and AU)
Preserved since onset, maybe ~2000
(Now, pretending we fast-forward until they've all been graded, because if I list the current graded counts, they'd seem way too scarce:)
MS65: 1800
MS66: 180
MS67: 18
MS68: 1
MS69: 1
Most collectors will hope for just getting a complete set. But the 'key date' will be the 2011 error coin. Then you'll have the MS-65 collectors, the MS-66 collectors...
Each will have its own price, each linked to the other prices, but independently driven by its own rarity, condition, relative rarity to other coins, etc.
My guess is that, because we're wired to think/react so strangely, the demand for these will start to increase once Bitcoin prices have unquestionably demonstrated they are again on an uptrend.
(If nightowlace is selling, I'd highly recommend him. Great guy, you'll get what you ordered, no surprises.)
PS - There are only 18 Version 1 100 BTC bars, with the remainder being Version 2. It's a damn shame you can't get them graded!