Right now Dynadot has the cheapest first year at $14.99, and Dynadot the cheapest renewal at $19.99. Over three years the lowest total at one registrar is $54.97 at Dynadot.
Why does .香港 cost more after the first year?
Many registrars sell the first year below cost and recover it at renewal: at Dynadot, .香港 renews at $19.99 after a $14.99 first year. Compare the renewal and 3-year columns before you buy.