Montech X3 Mesh, 6 Fans - 3X 140mm & 3X 120mm Fixed RGB Lighting Fans, ATX Mid-Tower PC Gaming Case, USB3.0, Door Open Tempered Glass Side Panel, High Airflow, Black

If you want to go value for fans: $76 Montech X3 Mesh, it comes with 3x120mm and 3x140mm fans. You could probably run them all on min settings and be just fine. There's el cheapo: $50 AZZA Fighter. Has 4x120mm fans and a mesh front, only $50 after $15 mail in rebate. A name brand option: $90 Corsair 3000D Airflow, comes with 2x120mm fans. Front PSU model: $130 Asus AP303 ATX over budget but is a "compact" ATX design. This one has no fans included so you will need a 3 pack.