根據Steam規範
https://support.steampowered.com/kb_article.php?ref=6627-QSNM-5276
I have moved, how do I change my store country?
If you have permanently changed your country of residence, you can set your
store country to reflect that. Go to your Account Details page and you'll
find Store Country in the right column under Your Steam Account. Once you've
selected your new country of residence, you'll need to verify it by using a
local payment method tied to a local address for your next purchase.
For example:
Say you've recently moved to the United States. You'll now see United States
as an option in the Store Country drop down. Selecting it will change your
store to display products and pricing available in the United States. To
verify your new country of residence, your next purchase will require a
payment method tied to an address within the United States.
How do I make a purchase while travelling?
Your country is now part of your Steam account, so no matter where you
travel, you'll see the store in your country's prices and be able to make
purchases as you would normally.
STEAM的規範是 當你永遠移居(permanently changed)至某國家
你才可以更改你購買的商店
Travel(旅遊/出差 都算) 則是用你本來的國家商店計價
當然 你人在中國的時候 可以轉換到中國商店
如果你有中國的付款方式 是可以買的
但合不合乎規定 你看條文就知道了
不需要板友跟你解釋
就不要好死不死發生問題時 你已經回台灣了
還是老話一句
跨區購買一定有風險
投資前請詳閱公開說明書↑↑↑