IEEE's MAC address allocations have a weird pricing structure.
If you want to buy a 12 (aka 4096 addresses), that's $855 one time (or $0.20 per MAC address).
However you can buy 20 bits of space (1Mil addresses) for $2,030 one time !, and 24 bits (16Mil) for $3,375 one time !
I somewhat question the desire to buy 4096 MAC addresses when 1 million is only around 2x the price.