They don't have to *BUY* any coins. They already have them!
Why would would you as a builder go buy cheap plywood when you already have enough for the job? Sure, it's cheap plywood, but all the money you have to buy the cheap plywood is spoken for... to pay the construction guy's salaries for a while. What are you going to tell your contruction guys... sorry, I spent all your salaries on more cheap plywood?
I would argue from an accounting POV that these discounted coins are a liability against the declared value at retail. If Joe Blow paid $20 for the coin and uses it at a $20 value, its a wash. But if Miner Bob redeems his coin for $20 and it only cost him $7, he sees an increase in value of $13. That $13 has to come from somewhere and it comes out of GAW's pockets.
GAW cannot control what buys/sells happen on the exchanges. That would be price manipulation. They can only control what happens on their exchange.