Second hand will do you better than 90% of anything new you can get for under $100USD, most are trash tier that are little improvement over integrated graphics. There may be compelling new models in the $150-200 range.
The Nvidia 10xx series are a solid choice for the performance over prior generations (go with 1060 or better). Failing that, a 970 or 780 or better will be in your price range.
AMD R# 200, R# 300, RX 400, RX 500, RX 5000 series are pretty good depending on what you can find. I think that will fit the budget range you are looking for with a solid performance uplift.