There's some pretty damn good deals going for RX 580s right now on Newegg and basically everywhere- I'd suggest looking at Reddit's
/r/buildapcsales for news on card deals including Vegas and RX X70/X80 cards, like
this MK2 RX 580 8GB on the US Newegg site for $299 + $20 Steam GC. Profitability definitely is dropping right now for GPU mining as a whole, but so are card prices, too. I'm personally not touching GPUs until things get better with profitability, as I see everything as high risk and low reward in GPU mining right now, but it's your call in the end to buy GPUs or not.
those are not good deals , most of my gpus rx series were purchased for $170 ti $240 max , and at that time profits and diff were way lower