A:Answer its a barebones case, you still everything else, hard drives whether you choose to do nvme, or sata-based ssds, or even sata based mechanical drives, and then a power supply, motherboard, processor, graphics card, and ram, and a heatsink for the processor.
complete systems wont be 300 bucks. more like 800 to 3k, up to you want you want to use it for.