I actually have a pretty good forecast with historical data in mind.
 
4482961509- 03/14       
5150199218 04/14      
5817436928 05/14      
6484674638 06/14      
7151912348 07/14      
7819150057 08/14      
8486387767 09/14      
9153625477 10/14      
9820863187 11/14      
10488100896 12/14      
11155338606 01/15      
11822576316 02/15
The miner is capable of 600 GH/S   

Here is a profit decrease model
 
1577.34      
1165.8      
1030.83      
923.63      
836.44      
764.13      
703.19      
651.13      
606.15      
566.89      
532.33      
501.67   

Profit lost in respective to the last known profit       
-411.54      
-135.8      
-107      
-87      
-72.31      
-60.94      
-52.06      
-44.98      
-39.26      
-34.56      
-30.66   

To be honest, Bitcoin is pretty profitable if you know what you are doing. There are many cynics out there that believe BTC is over excluding MTGOX victims.
If the numbers are true from the data then we can definitely conclude that as bitcoin grows more difficult to mine the hardware manufacturers will enjoy bountiful amounts of income. Many metropolitan areas have office space for lease between 150 to 300 square feet and the monthly rent ranges from $150 to $330 dollars excluding New York Dallas and etc. If one were to rent space many landlords include electricity costs within the rent so in my case I did not factor in electricity costs. I have noticed that they sometimes would come into the building and turn the lights off to save electricity but I told them in no circumstances can they touch the locked racks. If one were to reach above the 600 gh/s rate it would be wise to rent out space if expansion is wanted.

Thanks

P.S. The equipment I considered free because the expense was paid by a friend who I did a favor for in 2006.