Do you mean the air fare to HK? for this you may check from China flights(https://www.travelchinaguide.com/china-flights/) for details. Keep in mind that the ticket price is changing on different time. You do not need visa to Hong Kong for 14 days, but if you are going to or plan to stay there for more than 14 days, you can apply for a visa in advance. Or you can try to extend your stay at HK immigration before the visa-free duration 14 days runs out. Please keep in mind DO NOT overstay in HK.