I also just few weeks ago started researching about mining and highly interested to do in near future. Right now I am gathering all info about mining, hardwares, gpus and other stuff. So from my research I decided to buy radeon rx 570 8gb cards for eth mining. These cards are not so expensive and can produce 29-30mh/s which is about $60 per month (if you paying for electricity 0.1kwh).

Radeon rx 580 are more expensive and producing similar hashrate, so i really dont understand why people buying these instead of rx570.