about bitcoin market price for a shopping mall I am thinking of making a shopping mall based on Bitcoin payment system.

But, as you all know, bitcoin market price experiences sudden rise and drop nowadays and It will also continue to fluctuate in the future.

In this situation, how should I make my shopping mall using Bitcoin ?

Existing malls using Bitcoin are accepting that ? 

I have to change my product prices every time the market price of Bitcoin such as MTgox and BTC-e is changed ??

Does anyone have an idea about that?
There is a simpler option than to re-tag your products every day to keep up with ever changing prices. You could denominate the products in USD/EUR/... and advertise that you are accepting Bitcoin. Then you update your point-of-sale software to be able to do the USD/EUR/... to Bitcoin conversion on the fly, with regularly updated exchange rates. This way you always keep up to date, can give information on the current price in Bitcoin and accept Bitcoin payments, all while keeping the price tags stable.