Have you run the numbers to figure out how long it would have to run (how many blocks) it would take to pay it off and be profitable?
I see a lot of "Ok I'm buying this hardware!" and very little forethought in the profitability of the setup (which only starts after you recoup the cost of the rig).
This right here.
Also think about "plans for the future". Spending an extra $50 now for a larger PSU and a motherboard with an extra PCIe will save you a ton of cost/waste late if you choose you expand. Keep in mind your future goals as well before rushing out to grab new stuff.
Include power costs in this, we're entering the summer months and large parts of the US (if you're in the US) have variable rates for the power that is FAR more expensive in the summer.
Also, when doing any math here, given how fast difficulty has been changing, you're going to have a hard time getting long term numbers. For something kinda close, assume a 50% difficulty increase in every 2 weeks, its not really that exact and is almost a "worst case" scenario but it needs to be factored in. You're also taking a huge risk in that the BTC price is going to continue to increase relative to the difficulty, if that fails to happen, your daily income is going to be massive degraded in the very near future.
Buying no hardware is not a sure thing, like any investment you're assuming risk, keep that in mind. At least with BTC mining you have a physical item (PC, vidcards etc) that has a potential resale value if all of this goes tits up tomorrow.