In my opinion, it mustn't be about discounts as a business model, but more about accurate pricing that doesn't try to rip the arse out of the consumer.
When suppliers and such stop trying to rip us all off, they will see their businesses flourish.
Given the economic times we're in now, people are even more price conscious. Not related to wine, but its still a perfect example. 2 weeks ago I was in my local Spar and Coke was on special for R13.99 for a 2l bottle. I went in a few days ago, and its now R15.49 on special. Randomly chatting to my friends who use the same Spar. They all noticed it, were amused that Spar is trying such blatant BS and nobody has bought Coke, they've all bought Pepsi because its R12.99 for 2l and this is the standard price.