I'm guessing the GPUCoin price will be pretty close to what it costs to mine. If you have to pay more than the graphics card's price you want to buy - in electricity costs - it doesn't make much sense to mine, right?
You bring up a good point about the power costs. Actually, I had totally forgotten about the power cost to be honest. So let's toss out some data. I can personally ScryptN at around 10Mh, and it will use 7,000w/hr. If I mine for 24 hours, that's 168Kwh. If my Kwh cost is 0.11/usd, then my mining cost was around $18.50 for a day.
Speculation:
Let's say it takes 7 days to mine enough GPUC for a 270 series card. I spent $130 to pay for the electric. How much is GPUC worth at that point? The longer I have to mine for a card, the less perceived market value the coin may have based on electrical costs, because at some point electric will cost more than just buying the card outright.
Perspective:
I can get MSI R9 270's on Amazon for $150 fiat (last week's order).
This would demand GPUC be worth much, much more than it is now.