Del, check out the reviews of the new AMD Ryzen 2400G - this CPU has built-in Vega graphics, and it is able to play some high end games at low/medium settings with decent frame rates. I am hoping somebody will try it with AH3 out and report results to us. You could add a video card at a later date with a system built around that.
Otherwise I think a $250 1050Ti would be a reasonable starter card you could get by with until prices come down. I have an 4Gb Radeon RX 480, prolly roughly equivalent to the 1050Ti, I get 60 fps at default graphics settings - which include shadows, reflections, etc. I am running at 1080p. The miners aren't going so much for the lower end cards, so the prices aren't so outrageous and stock should be available. You still have options.