Originally posted by Edmund
If you stand on the side of the building where Cathay Photo is and look across the road to the opposite building, you will see a post box. To the left of the post box is Watsons and to the right (when you are looking straight at the post box) will be an entrance into the building. Walk straight in and Camera Workshop is on your right just before reaching the "mama" shop at the end of the corridor.
As for the prices, you can bargin further.