Why is the notarization of marriage certificate in Hong Kong so expensive?

Because it contains a lot of handling fees.

The notarization of marriage certificate in Hong Kong needs to be handled locally in Hong Kong. This fee includes notarial lawyer's fee, transfer stamp fee of China Legal Service Hongkong Co., Ltd., agency fee and document delivery fee.

It takes 1 week to notarize the marriage certificate in Hong Kong. The notarized materials shall include the original Hong Kong marriage certificate and the scanned first page of both spouses' passports. China entrusts a notary to notarize, and then sends it to China Legal Service Co., Ltd. with the transfer stamp. This is the authentication procedure for sending Hongkong documents to Chinese mainland.