this is not a computer hardware forum... want price list can go HWZ or VR-Zone.
what i can probably say, cost efficiency, get a 3.5" 1TB now. 2TB still kinda expensive. 500 are dirt cheap, but kinda waste of space imho. I've changed all my 3.5" inside my chassis to 1TB, with a velociraptor as boot. 6x Sata HDD & 1x Sata DVDRW, cos not enuff Sata power connector from PSU.
For backing up, WD Black & Green no diff. Price got diff. Green about 130-150, Black 170-180... current price.
If using for boot or running programs, recommend using WD Black.