I am a beginner looking into Bitcoin mining. I don't want to waste time (or electricity) so I started looking into hardware mining rigs, for example: Saturn
priced at $3000 USD, 275GH/s, consumes ~400Watt (or even Monarch from butterfly labs which claims 600GH/sec @ 350W, priced $4700)
I put these numbers + my local electricity price + current difficulty into a decent calculator, and I get >7,000 $USD profit for 3 months time frame (or >18,000$ for the Monarch). Sounds a bit too good to be true.
I know BTC/USD rate might fluctuate, and that the miner will produce heat, but still. - Where's the catch/mistake, if at all?