At that kind of price level, you're most likely better off looking for a used/refurbished system with a not-too-ancient mid-range CPU, and maybe adding a low-power graphics card to it. There are some used small form factor business PCs on eBay with 2nd and 3rd-gen i5 processors for around $100 or so, that you could then add something like a GT 1030 graphics card to. Just make sure the PC has a PCIe x16 slot available for the card, and if the case is a small form factor (SFF) size, go with a low profile GPU. Ideally you would want it to have a 300 watt or higher PSU, but a GT 1030 is only a 30 watt card, so you might be able to get away with less than that. A used PC with something like an i5-2500 that has had a GT 1030 added would...