so if yo want to explore HK n your set up is short-term then it's $55 for a tourist day pass, 30-40 for food, 100-200 for accommodation( very tight ) /day. Say $250-300 in total/daily expense.
But you really only need 5-10 days here..........
btw, there are similar threads
"HK on the cheap" or something like that, just browse the forum