> does that mean if one is to use a locally administered address a device is free to take whatever they please?
I think those have traditionally been set by network admins, not randomly chosen by devices, but pretty much: nobody apart from local admin coordinates addresses with the local bit set.
> What would be advantage of paying to the IEEE for a universally administered block?
The promise that no device built by other legit companies will have an address from that assigned block, so customers won't have to worry about MAC address conflicts, provided they use only widgets from those who honor the assignment scheme.