Can't seem to find a motherboard that would support the CPU and DDR3 RAM that is $50 or less. If you plan to overclock, getting a Z170 DDR3 ATX motherboard would cost you about $110++ (http://pcpartpicker.com/product/KmgPxr/asrock-motherboard-z170gamingk4d3). If you don't plan to ever overclock, getting a B150 DDR3 ATX motherboard would be around $100 (http://pcpartpicker.com/product/7TnG3C/asus-motherboard-b150prod3).
If you do plan to overclock, you would have to buy an aftermarket CPU cooler to solve the thermal problems. For $30, you can get the Cryorig H7 (http://pcpartpicker.com/product/93Crxr/cryorig-cpu-cooler-h7). For less than $20, you can also get the lesser-powerful Cryorig M9i (http://pcpartpicker.com/product/LPVBD3/cryorig-cpu-cooler-m9i).
If you don't plan to overclock, then the stock Intel CPU Cooler will suffice.
As far as your PSU is concerned, that EVGA 500W has sufficient wattage/amperage at the +12V rail to power your rig. However, in terms of quality/warranty/efficiency, that PSU is not the best out there. I would look into getting a Seasonic (such as the G-550) for said purpose, though it costs ~$70 (http://pcpartpicker.com/product/DPCwrH/seasonic-power-supply-ssr550rm). A slightly affordable alternative is the Seasonic M12II-520 at ~$60 (http://pcpartpicker.com/product/TgW9TW/seasonic-power-supply-m12ii520bronze).
If you want better price/performance for the RX 480, you can get the 8GB version for roughly the same price as your initially-selected MSI Gaming X 4GB (at $207). The XFX Radeon RX 480 8GB is only $210 (http://pcpartpicker.com/product/29wqqs/xfx-radeon-rx-480-8gb-rs-video-card-rx-480p8lfb6).