i agree on the pricecheck Jonas gave for the Robe of Britannia "Ari" robe, but yours isnt that. Its "Bal"
Ari was originally a 1 of 3 (arirang), "Bal" was a 1 of 1 (balhae)
Ari was massively duped, and even has a replica. if you search stratics theres tons of selling posts for it.
Bal was not listed on thomas bryces dupe thread at all, if it was duped, it was much more lightly than the Ari one. theres 0 selling threads on stratics that i could find.
So i think the "bal" one is worth alot more than the ari one. but youd have to find a serious clothing collector, someone who cared about the slightly different names, different shard, different histories.
Very hard to put a price on it but if i had to, id say anwhere from 1-3 bil to the right collector.