Yeah, it's crazy. I watched 38Gh/s miners go for $500+ on ebay. That's more than $12 per Gh. People buying like that are what's making the price go up. A Gh is not worth more than $3.
People could mine altcoins with sha-256 equipment, just for fun.
People may not be ready to spend few K dollars for 1TH machines but $500 is ok to loose. My 2 cents.