Thanks for the reply!

I chose the Saphire RX580 to keep my options opened. Many people told me to mine Ether, and that's why I chose these cards.
But I thought, I'll start with Bitcoin, and see.

Also, for the future, in about a year or two, I can always add more newer GPUs, and keep these ones to mine other easier cryptocurrencies.

And for Electricity, yeah. I never started because it was a big cost factor here in the US. But thankfully I found a great way around.