To save the $100 I would look toward the case and power supply. Both items you have choosen are great, but you can save money without sacraficing quality. Case is more of a personal choice so I'll let you look at options there... For a PSU look at the the XFX Core Edition (currently has rebates), Seasonic or Antec. Don't put too much stock in a modular PSU unless you have a micro case (which you don't).
The Biostar motherboard may be fine, but I always go with ASUS, Gigabyte and ASRock (and in that order).
On the memory front, up that to DDR3-1600 1.5v CL9. Should be the same price as DDR3-1333.
I linked the 520W modular Seasonic. It's able to deliver 40 amps of 12V power. That's better than any other you will find, unless you want to pay a lot more. Take for instance the 600W OCZ modxstream Pro... 42 amps, $80, and made by Sirtec.
Our test system is based on a power hungry Core i7 965 / X58 system. This setup is overclocked to 3.75 GHz. Next to that we have energy saving functions disabled for this motherboard and processor (to ensure consistent benchmark results). On average we are using roughly 50W to 100 Watts more than a standard PC due to higher CPU clock settings, water-cooling, additional cold cathode lights etc.
We'll be calculating the GPU power consumption here, not the total PC power consumption.
Measured power consumption R7850 power Edition OC
System in IDLE = 158W
System Wattage with GPU in FULL Stress = 254W
Difference (GPU load) = 96W
Add average IDLE wattage ~10W
Subjective obtained GPU power consumption = ~ 106 Watts