UPS (Need Advice)
Not for backup time but mainly to turn CPU OFF upon electric failure (there are plenty in my location). It will be good if this UPS could turn PC back ON after electric power restoration. APC 650VA (P/N BK650VA) - 110$ http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Other available resources
=================== http://galaxy.com.pk/ (Prices are 100 times lower for USD. e.g. 1000 = 10$)
CPU: If only for gaming then i would go for the i5 2500, the difference between the two is not noticeable in gaming and it saves a lot of cash.
CPU Cooler: If no overclocking then stock should be more than enough so none needed.
Mobo: I like the Sabertooth very much, but to get the full benefits you will need a 50mm fan to go on the board to allow the TUF armor to operate effectively.
Chassis: HAF X is a very good choice.
Graphics Card: I would personally go with the EVGA 570 if it is to last that long, or even dual 560Ti's.
I realize that you said that you will add another card in 6-8 years, i think it would be best to just buy an entirely new graphics card then as the technology is progressing really quickly (try and think of a GPU from 6 years ago and compare it to the cheapest on offer today).
PSU: The Corsair 850W is a very good choice and leaves a bit of head-room for upgrading. Also, non-modular is the way to go if you don't mind having a lot of wires floating about in the case (will not be a problem with the HAF X)
I can't really advise any more as i do not know the American market very well (i'm from the UK), however my final piece oof advice would be to get an SSD as these provide a noticeable improvement in general speed and responsiveness. Something like the Crucial M4 will do just fine.
With regard to the 50mm fan, essentially too allow the TUF armor to operate effectivly there needs to be airflow through it. This can either be done through a top-down CPU cooler or a 50mm fan for which they have a slot for.