It's my almost 1.5yr old pc with a GTX 1070. That's the only gpu I have right now.
I build that pc for around $900 USD for my college work and VR development on Unity3D.
But started mining just a week back using nicehash, I'm also thinking of adding another gpu (GTX 1080 TI maybe) soon.

If you are starting out for mining from scratch I would suggest to stay away from AMD gpus coz they cost same as nvidia ones but use more electric power to run. In comparison my 1070 uses 150W for the same or even better performance than RX480 that uses 250W.

Use the nicehash profitability calculator (https://www.nicehash.com/profitability-calculator) to estimate your daily earnings.

Have fun mining :)