Just got a message from www.smsl-topping.com, they seems offer free DHL shipping, 30 days free return, and they will give back the price different if you find lower price from other place.
Yesterday I got the first batch of TOPPING D90, cost me $689.99 but they sent by DHL (https://www.aliexpress.com/item/4000470941560.html ), that's really a great DAC! Lol
I just heard another MQA DAC has been released: SMSL M500, Price only 399.99 US dollars.
https://www.smsl-topping.com/SMSL-M500-MQA-dac-Headphone-Amplifier-ES9038PRO-AUDIO-Decoding-USB-DAC-p2239900.html