Anyone looking at ROI's shouldn't even go 5 btc after the massive diff increase today, and the recent price hike. Even turning down tgb's crazy diff estimates to 50% per diff period, 5 btc doesn't pay off itself... ever..
http://mining.thegenesisblock.com/a/31899df662These don't use 360W each. They use 220-240W each. And for those of us who have extremely low power rates, it's even that much more profitable.
That said, I don't disagree that 5BTC is too much.
I'm paying 0.07BTC/GH, which means I'll pay 4.2BTC per 60GH Single.