Wing Shing and Man Shing are basically the same shops, same owner. Their prices are getting less and less attractive. Tin Cheung is one of the better shops and there is another called Kowloon Camera which is located in Jordan/Temple Street, located opposite Eaton Hotel, one street behind.
Kowloon Camera shop offers better prices than Wing Shing/Man Shing. I buy most of my stuff there. Though the latter offers more variety than Kowloon Camera.