How exactly does buying across worlds work?

There's that and buying expensive items, server transfering, buying the item you want with mesos, then transfering back. That's REALLY expensive (50 dollars) and it doesnt really work as Scania is kinda the most inflated server (Im having trouble finding things to bring to Windia x_X)

You can easily xfer between servers using MTS. Place a request for your own item in "Wanted" on one account on the server to be moved to... type in the exact stats of the item you want to transfer, and place like a 220 NX price tag on it. Then go to MTS with the other account, which is in the server you're transferring out of, look up the original account's wanted tag, and sell your item to yourself for 220 NX. The item is then transferred without any world transfers. The only limitation is that you cannot transfer items which are not currently listable in MTS.