A bit of an odd question

I'm currently building a PC, and I have everything laid out for it. The only thing I'm missing is a power supply. Now, before everyone starts shouting out names, lemme give you the reason:

 

My wattage is estimated at about 350 watts. Now, that's nothing impressive, but the kicker is that I'm looking for a PSU that will give me the best efficiency at 20-50% capacity. Obviously I'm going 80 Plus certified. But, not all PSU ratings are the same, even though they have the same seal of approval. Most sites don't offer the efficiencies at all, unless they say "<80" "80 Plus (certificate metal here)"

 

My question is: Which PSU will give me the best efficiency at 20-50%? Keep in mind, I'm on a tad bit of a budget ($75).

How about a general idea of the hardware you are using so we can figure out what type of power supply you need since it's probably not going to be modular on a budget and would be nice to see what specific connectors you might need.

 

80 plus doesn't just mean 80% @ max load. to be rated 80plus it needs to meet other requirements @ other %loads

What is the rest of your system? A lot of online wattage calculators can be relative


Parts list: 

http://pcpartpicker.com/p/1bfZA

 

And I know that. 

In that price range you can't really go above 80plus bronze So here's what i'd recomend

Seasonic SC12 II 520W 

http://www.newegg.com/Product/Product.aspx?Item=N82E16817151094

Also- please move this to the PSU hardware-subforum.