i want to know the cost and requirements of travelling from ghana to hongkong as a tourist with an invitation

It costs around HK$160 IF you apply from the HK Immigration Department. It takes about four weeks to deal with your application. And you can apply from the Chinese embassy in your country too. The required documents are: your passport, filled ID1003A form affixed with a recent passport size photo, copy of your passport infomation page, financial statement, transportation itinerary (flight for example). If you have a sponsor, he/she needs to fill the ID1003B form and provides copies of his/her HK ID card and passport.