thx for the r8ing
fans are r8ed with 2.4 watts although you can also attach it to 5V usb instead of 12V. Then you have 1 watt. Normal fans are r8ted with ~40 Watts. But typically those have lower fan settis as well.
Cost wise I paid 3.5€ per fan and 3.8€ for the two wire fan grills at front and back. I feel like I overpaid for the fan grills and it might have been way cheaper if I had ordered them directly from china. Those grills are necessary though because it is easy to break the blades if you accidentally come in contact with it while its running.