For me, it's a no brainer, just go straight to Johan Foto in the 4th floor of Plaza Angsana, don't even need to waste time at other shop seeing other people's black face and bad attitude.
The boss, Anthony is there most of the time. His staffs, Ah Mun and Ah Leong also very friendly. He have a partner, if I did not recall wrongly, name is Helmy or something, also a very nice guy. They allow you to test their stuffs before buying and no black face at all. Most importantly, after you have "warmed up" with them, you can bargain the price with them nicely. Just remember they are running a business, so do not low ball like you do in B&S. Normally if you are sincere, humble customer, you should be able to pull it off.
That said, I may be visiting them over the next few days again....
Edit: I hope they can look for a shop lot at somewhere better. Plaza Angsana is not a place you wanna stay long. I suggest if you do go there, you buy and go, don't loiter in that place.