Prices for Sony is always controlled. Ask any of the shops and I doubt that is the reason they "can't" give discount. I would be more inclined to believe that they "do not" need to give discount now given the demand exceed the supply. Why give discount when you don't have to.
Having said that, I am pretty sure if you approached them nicely/appropriately, discounts can be obtained (especially for regulars unless they really don't mind losing the regulars). The question would be the quantum of the discount

($1 off the retail price is also technically a discount).