I think the price for GPUC should remain fairly stable,  once the store opens up and we have some idea about how many GPUC it will cost to get one GPU.   I think the GPUC should be in some way self-correcting because anyone who buys GPUC to get a GPU is going to check it against the value of BTC and their national currency.  If it's too much, they won't buy.  If it's too little, the sellers won't sell.  The volatility might be more connected to BTC volatility than manipulation of the GPUC market.

The only way I see extreme volatility is if there's a lot of dumping all at once or if the GPUC store is the only place where you can find, for example, 290x GPUs.