That case seems to come with two 120mm fans on the side panel. There is mounting for another at the front and an 80mm fan at the rear. I'd think you would want to occupy those spots, front 120mm as intake, the rear 80mm as exhaust. Here's what I would do with that case... take the lower of the two panel fans and move it to the front as intake, ensure the top panel fan is set as intake, have the 80mm at back as exhaust (I already said that) and situate the PSU with the fan down (toward the inside of the case - very important, you'll want to do that anyway). You should be set then.
So, according to my plan (we'll call it the Friedman Plan), you'll only need to purchase an 80mm fan for the rear of the case