Remember, don't invest what you can't afford to lose because *anything* could go wrong, you may indeed reach ROI but you may not depending on when you actually buy, the pool you use etc etc....no guarantees at all and if BTC goes down to half the price it is this morning well you can already imagine what that means.

Personally I don't trust the mining profit calculators and don't find them accurate compared to my actual real world results but again do NOT spend what you can't afford to lose as things are getting late in the game and soon 200 GH/s will be worthless. I have four of the Antminer S1 and can't see them being very profitable after another 60-90 days and their will come a point where power costs more and it will be better for me to sell them all and hope someone with a larger farm that doesn't pay power will want them. I may be wrong and perhaps they will last a bit longer but nobody really can be 100% accurate and if we get flooded with 2 TH/s miners soon that will affect things.

Don't forget the cost of power! I have a power monitoring system and can tell down to the cent what each watt cost and overclocked my Antminer S1's for two of them in my home are using 864 watts and I pay 6.99 kWh this month so I am paying about $1.40 for two units per day and $2.80 for all four of mine per day to run 24/7.

Simple math says all 4 of my units will cost me $84 in power this month but what if next month my power goes to 12.35 kWh which alot of times does happen, well then I pay double the cost for power. I am currently making about $60-80 per day on average from what I can tell however difficulty is increasing and this will get less and less so I don't need to say it again because I already warned you twice about your investment. :-)

I cannot post a image and get an error "invalid proxy" when using imgur otherwise I would show a capture of my power usage for two Antminer S1, I'm sure others get the same numbers as I do in regards to power usage etc.

Good luck!