Can I get Chinese visa from hongkong & what would it cost &where in hongkong will i need to go 4 it.

Indians are not allowed to get a China visa from Hong Kong.

But if you have the following requirements, it is possible for you to get SINGLE entry China visa valid for 15 Days in HK:
Previous used China visa on a new or an old passport;
no cancelled china visas;
a confirmed return ticket or a ticket showing exit from China;
a confirmed hotel booking voucher.
You should go to Visa Office of the Commissioner of the Ministry of Foreign Affairs of the People's Republic of China in Hong Kong SAR to apply for the visa. The address is 7th Floor, Lower Block, China Resources Building, No.26, Harbor Road, Wanchai

You may also get a China visa from CIS at Hong Kong airport at certain charges.