Because it's twice as good as one standard Realforce keyboard.
And why is that?
Well it was made mainly with aluminum, but the secret ingredient was love.
But seriously, aluminum cases for MX switches never made sense to me, b/c they can get very pingy. But with Topre, that wont happen, you'll get the awesomeness of the aluminum case (mainly the heft, if you've never had an alu case, they are extremely heavy by keyboard standards), matched with the "thock" of the Topre switches. How can you compare that to even three standard keyboards? You can't. It's ridiculous to compare them at all. Get one standard and one aluminum, or aluminium if you're British.