I think mining would be possible but do not expect to gain much from it; I think most get much from it from trading.
with 200MH/s u can get around 1ETH/month...it's not a lot but it's something...trading is too much stress for me
You need minimum 6 cards RX 580 and overclocked and bios modified in order to achieve that hashrate, the cost is not small for mining ethereum. Now I see there are some signatures that are paying in ether tokens which you can sell or convert to ethereum but I don't know how it works in depth.
i've got 9 Gpu's rx 470 8gb but they are not overclocked...yet
u got it right about investment...in cost me around 4k$...at the moment i'm not familiar with those signatures so i have to learn about that to...