Could someone pick all the parts to make a Bitcoin mining PC. I will only be using it for mining Bitcoins. Also I can only afford $900 - $1000.
Bitcoin mining with graphics cards isn't practical anymore. The electricity you use to power your system while mining 24/7 will cost more than you will end up making in bitcoin, so you will lose money.
Do you realize that you're the reason why GPU prices are inflating?
Anyway I recommend ASIC machine instead.
Now bitcoin is hard to produce in GPUs, even litecoin which is a cheaper currency is now harder and harder to produce every day.
I recommend BFL SC 50 Gh/s, MinersCube 5, and KnCMiner Mercury.
Or if you prefer FPGA I recommend Avnet Spartan-6 LX150T Development Kit, ModMiner Quad, and ZTEX USB-FPGA Module 1.15y