Need suggestions for case fans

At this moment I only have one noctua fan and it's only moving about 1500 rpm.

I need some suggestions for new case fans that can move a lot of air . I don't know if I'm really concerned about quietness for the fans. I'm more concerned about keep my case cool.

I'm not concerned about price, but I want to get a great product.

You're looking at this wrong. The speed of the fan in RPM does not solely indicate its performance. In stead: look at the CFM (cubic feet per minute) this is a measurement of how much air the fan will actually move. The Noctua fan is moving a lot more air than you'd think, even at 1500 RPM.

You can use these, but only if they are in a tight spot like in between the front and the hard drive cage where the static pressure would be useful, other wise look for some good air flow fans, like the corsair af120s.