It's been hovering around $16-$19 per GH for the last few days which still seems a bit too high for me.
It is better to think in terms of BTC rather than dollars because mining generates BTC.
Consider this: if BTC dropped in value by 90%, then the price for 1 GH/s would become between $1.60 and $1.90. Wouldn't that be an awesome deal? No, because the revenue (in dollars) from mining would also be cut by 90%.