shoot a few emails to those who make replicas, lots of names there:
https://chinertown.com/index.php/topic,5263.0.htmlyou can also email airwolf via aliexpress, they specialize if buggy replicas.
all of these are able to paypal / swift / wechat payment transactions and ship you something. if it's outside of aliexpress, shipping alone will probably be c.25$, but the seatpost could be as low as 20 bucks potentially, and should really be under 50. if they have the reference you need, obviously.
350 for a seatpost is just insulting.