Bios mod is not that hard, just follow the guide
I would go for 1060s, they priced around R3900 atm on wootware.
6x 1060 makes around 22 usd a day. R23400 for 6 cards.
6x rx 580 makes around 31 usd a day. R37200 for 6 cards.
Can you send me a link to the 1060's at that price please (or which one you think is best to go for)?
Want to try order everything I need today still.