This is assuming you have these parts already owned:
1. GPU
2. CPU
3. Motherboard
4. Hard Drive
Basically what you need right now is a new:
1. Case
2. PSU (Power Supply Unit)
3. RAM (4GB is obsolete so I managed to fit in some 8GB of Corsair Ram - *Note - If your board has 4 slots for ram and you wish to have 12GBs total, make sure the 8GBs that you buy are THE SAME CLOCK SPEED. That is extremely important as you may run into compatibility issues)
Here is your build
Enjoy!
Because the motherboard is what i don't know if you can reuse, i made two builds:
Build 1 (Assuming you have a motherboard):
PCPartPicker part list /
Price breakdown by merchant /
Benchmarks
Memory: Corsair 8GB (2 x 4GB) DDR3-1333 Memory ($58.99 @ Amazon)
Case: BitFenix Merc Alpha (Black) ATX Mid Tower Case ($49.99 @ Newegg)
Power Supply: Corsair Builder 430W 80 PLUS Bronze Certified ATX12V Power Supply ($24.99 @ Newegg)
Total: $153.97
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-07-01 20:15 EDT-0400)
Build 2: If you dont have a motherboard: *Note that this does hit $180, i picked all the parts for a specific reason, so you shouldn't change it without asking
)
PCPartPicker part list /
Price breakdown by merchant /
Benchmarks
Motherboard: ASRock H61M-DGS Micro ATX LGA1155 Motherboard ($44.99 @ Amazon)
Memory: Corsair 8GB (2 x 4GB) DDR3-1333 Memory ($58.99 @ Amazon)
Case: Thermaltake Commander MS/I Snow Edition (White/Black) ATX Mid Tower Case ($34.99 @ Microcenter)
Power Supply: Corsair Builder 430W 80 PLUS Bronze Certified ATX12V Power Supply ($24.99 @ Newegg)
Total: $198.96
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-07-01 20:16 EDT-0400)