76BTC for 10Gh/s.  At $130/BTC that's $9880.

Buying 15 7970s would cost around $6150.  Also buying 15 7970s would draw 3750 watts per hour or $13.5/day (at .15 per kW/h).  Running 3750 watts per hour for a year equates to about $4927.5.

Thus buying the blade for $9880 is equivalent to buying 15 7970s and running for over a year.

Of course you wouldn't be able to use the Blade to create 15 separate gaming PCs.