IPv4 addresses must really be running out

The IPv4 address space really must be running out. Today I received the following spam:

We are currently seeking to enter into direct lease with respect to any of your unused IPv4 netblocks.  We pay Competitive lease rates via wire transfer and close transactions quickly.  Our lease/rental of your IP space will always be governed by best practices. If interested, please respond to this email and we can work out the details.

Someone is getting desperate - or spotting a business opportunity.