If you guys could go ahead and restrict the use MBs while being on another world

[Seraphor]

Then let sellers sell on those other servers or link all MBs up (per data center of course).

Otherwise get rid of being able to buy on other servers.

Why is it either or?

They will eventually introduce a cross-world marketboard, until then, buyers have choice, there is no downside unless you're a price gouger.