Even if you managed to acquire them, the IRR's could claw them back (in theory).
you might have to buy some really big military contractors to pull that off, though :)
ARIN has the most ridiculous policies on IPv4 space and RIPE actually has the best, in my experience.
IPv6 is coming no matter what and a healthy IPv4 market is not going to stop that. The IPv4 market improves efficiency by re-distributing the addresses to people that actually need them.
Right now there are millions of addresses in the hands of people that don't even need a single IPv4 address and often don't even remember registering the space in the 90s (IPs that have not been publicly announced on the Internet for decades). They gave out too many addresses to the wrong people in the 90s and an open market will help distribute it to the people that have a technical need for them.