Hmmm... Considering the rather poor scaling of typical SLI (two cards, twice the cost, twice the power consumption, maybe a 5-25% performance increase, depending)... I wonder what you get with four cards, and four times the cost, and four times the power consumption?
Heating Bill -$200
Saving on winter clothes -$300 (You won't be going out anywhere)
Saving on nights out -$500 (see above)
Pure gaming joy, bragging rights, and not being able to hear your missus over the whine of all those fans?...