Just a suggestion and feel free to ignore but a good way to experiment is to pick up an old dual core machine like a lenovo think centre, or similar, and use a single NVIDIA 1050 or 1060.  It'll let you do most things.. it takes about a week / two to reach the payout required for more pools but it's a cheap way to get a tiny rig going and the 1050 / 1060 shouldn't require any additional power depending on the second hand machine you get.  You could go AMD as well but I'm not sure how much power the low end AMD cards draw.

I started this way and got a $20 machine from my local newspaper and a  new 1060 on sale from Ebay.. I later sold that original machine for $50 ($30 profit) when I upgraded and built more.