* Mikael Abrahamsson
Otoh, ARIN isn't exhausted yet so getting IPv4 addresses there should still be a lot cheaper than doing CGN?
From what I hear several ISPs in the ARIN region prefer to obtain second-hand IPv4 addresses (or deploy CGN boxes) over requesting addresses directly from ARIN, and the reason is that ARIN, per policy, will only give its members addresses to cover three months' worth of consumption, and that this period is simply too short for the allocation to be operationally useful, especially for large organisations.
I have an anecdote to share here: A while back, a techie from a large organisation in the RIPE region told me that from their point of view, the RIPE NCC was effectively depleted once they implemented the three-month period for allocations on the 1st of July 2011, because they needed more than three months to actually put a new allocation in production - hence they couldn't justify anything any longer. When transferring, on the other hand, ARIN's policies allows for obtaining up to 24 months' worth of space. This gives longer-term operational predictability, which may easily justify the cost of the addresses themselves. Same thing goes for deploying CGNs instead - the organisation is then free to plan as far ahead as it feels like, without being constrained by ARIN policies. That has a value, possibly more than the cost of the CGN boxes themselves. Tore