I am having this issue with my Nissan Qashqai on my front suspension.
Creaking sound when hitting the bumps and braking so, I think the culprit is the shock absorbers but I have no idea which part to look for and how much does it normally cost to replace the shock absorber for the particular make.
Also please recommend best mechanics to do this job done in Sydney.

Don't self-diagnose, take it to a mechanic. Sydney is a big place, where is most convenient to you?