dont worry PSU's are not as difficult as u think
just 2 things:
power and brands.
corsair, seasonic, are good and trusted brands just a few of them ofcourse
if u want a detailed infohttp://www.tomshardware.com/reviews/power-supply-oem-manufacturer,2913.html
a very recent tom's article about it.
or just go with one of the brands and get a ~400W PSU
a little less wont be a problemhttp://www.newegg.com/Product/Product.aspx?Item=N82E16817139026
it might be a bit more than u need but it will last longer and a PSU is really important so i dont recommend people to go cheap on that
this one is also decent enough toohttp://www.newegg.com/Product/Product.aspx?Item=N82E16817371029