It would be very interesting to know what will be the cost of video cards rx580 by piece and if purchased wholesale. Could you then unsubscribe as you will know... 
I can buy these for 530 EUR. But, I wnat to know what I can mine with it? Can I mine multiple curencies or ETH only and also I want to know amount of Mhs? 6 GPU rig is going to cost me around 3.5K EUR... Thanks!
You can mine more coins with them, e.g Monereo, ZEC, ETC, you can dual mine as well (with Decred, Sia coin, Verge, ...) and so on. The Hashrate of a RX580 is around 30 to 32mH/s for ETH depending on the brand and the memory. 530 is a little expensive. Not sure which country you are from. I bought mine in the Netherlands for 300 to 350. So you might do a trip there as it could save you some.