Some industry experts say the black market for IPv4 addresses that economists have been predicting for some time is already here. Accoridng to this Ars Technica report, however, the economics simply don’t work.
“Getting addresses from the local RIR is basically free—even today. The procedures are tedious and you only get as much as you can show you’re actually going to use, but even if you get the smallest possible block (a /24 or 256 addresses) you barely pay more than a thousand dollars in yearly registration costs; having a lawyer review the contract that you have to sign for all of this is probably more. And the costs per address go down as the number you hold increases. So obviously there is little reason to “buy” IP addresses on the black market today. That will, of course, change once the RIRs run out of IPv4 addresses. At that point, “investors” that bought up the assets of ISPs that went bankrupt may be sitting pretty, just like HP, which now has two /8 blocks to its name. That’s right: HP has nearly one percent of all IPv4 addresses—it got block 15, and then it got block 16 after buying DEC.”