I would say this is kinda a tough one, but I may have a solution. Either get a 580 8GB or 1060 6GB in the mid $300 range new, or, if you consider used, you could get a better card such as a Fury or 1070 for around $400 or a bit less. You might even be able to get a great deal on the Fury, if you don't need more than 4GB of memory. A 1070 or Vega or higher is not going to be under $490 new, at least right now.