I am getting a A320M-ITX, not A320TM-ITX once I clear up some space. I don't have either at the moment.
Shipping for an ATX motherboard was about $40 through DHL from Shenzhen, China to Michigan, USA and took about 4 days. Unless your getting it express, that seems high.
I posted the Tmall link for the thin-ITX version on what appears to be ASRock Tmall store. Not sure if its official but they have seller guarantee and accept credit cards.
The gist of Taobao / Tmall for international customers is a two step process:
1) Ship items locally in China to a consolidation warehouse near an international center
2) Combine multiple packages and ship internationally.
Sometimes sellers will ship international directly. I highly recommend chatting with them first no matter what you decide. I also check their reviews / ratings and look for 4.8/5 or higher across the board.
Another option is shipping agents like Superbuy. They take care of everything and include pictures / inspection which is nice. Their international shipping estimator is here: https://www.superbuy.com/en/page/query/freight/ . Its a good reference point for how much international shipping costs.
Good luck.
