Typically plasma cutters will cut the thickness they are advertised
for, EXCEPT they'll do it very slowly, there will be excessive dross
on the bottom of the cut and the kerf may not be straight or even. But
it will hack through the material. Those thickness "ratings" are
for plain carbon steel under good conditions. I've always planned to
DOUBLE the capacity of a machine compared to my everyday work.

I would avoid mail order / imports because of consumables. Generally
the consumables are not interchangeable, some have a short life and are
expensive. Think of a cell phone. They give you the phone because you
buy the minutes. Here they "give" you the plasma cutter because
you buy the consumables.