[1] http://arstechnica.com/tech-policy/news/2010/07/internet-wil...
Mind you, that "right price" will start going up pretty quickly. Supply is fixed, but demand is growing pretty quickly. To some extent you can't see how fast the demand is actually rising because it's already hidden behind large NAT installations and such. The usual microeconomic equations for computing this sort of thing usually have a built-in assumption that for the right price production can be increased; when production absolutely can't be increased the price tends to rise faster than you'd expect. I don't know that there are very many blocks that are allocated but not actually used anymore, you'll be paying people to drop their block and pay the price of transitioning to a NAT setup or something, which can be quite painful.
So people watching the free-IP-block count aren't really watching the right number. The number to watch is the price of an IP block. Since I think the price of an IP block right has discounted into it the fact that we're moving to IPv6 and the crisis will be averted, it probably isn't as high as it would be if we weren't expecting to move to IPv6.
And so the real problem isn't really the "running out". The real problem is that IPv4 address as a limited, and therefore expensive, resource is just stupid. Yes, the market could allocate it efficiently, but it's better for everybody if it simply isn't effectively limited in the first place.
And then the consequence of that is that you end up with a lot of people talking past each other; "well, if it isn't running out what's the problem then?" The problem is that in 2016 a startup's largest expense shouldn't be their public IP block.
(That we are able to re-allocate, and thus, resell previously allocated blocks/addresses only means that there is a market, after all blocks have been allocated.)
On May 28th of this year I wrote an article:
https://secure.grepular.com/Setting_up_IPv6_is_Easier_Than_Y...
At the time of writing, they were predicting we had 427 days left. Today they're predicting we have 281 days left. It's gonna bite a lot of people on the ass.
My bad. :)