Which China A Shares TECH ETF have the lowest cost?

Specifically for A Shares, I think CNYA might be your best bet (0.60%).

There are other china ETFs though if you wish to consider them. For example, FLCH tracks large and mid-cap Chinese companies for only 0.19%. CXSE is a market cap weighted index of Chinese companies which excludes state owned enterprises (defined as more than 20% govt ownership) and they charge an expense ratio of 0.32%.