Two things- First, plasma cutters- Metalmuncher has it right on- those things are cheezy and have numerous design flaws which will drive you crazy from the get go. Bad motors, bad frame design, woefully underbuilt, crummy software, no real machine torch, no decent feedback circuit for auto height adjust, and on and on.
A decent machine will cost real money, unfortunately-
I have a nice cantilever style machine that was originally designed to cut 4'x4', which I have since enlarged to 8'x8'. Mine is just optical trace, no computer, and it was around 10 grand for an industrial quality machine- figure a minimum of 25k to 35k for a decent 4x8 industrial quality cnc machine.
Second- arty cutouts- I have made some portion of my income from arty cutouts for over 20 years now, and I would not recommend it to the sane.
As mentioned, there are tons of people cutting out patriotic eagles, fake Hopi indian designs, flowers and animals. Most of these are very low quality, poor fit and finish, and sell for under 10 bucks. There is now way any one with any self respect can compete with this crap. More and more of it is coming from offshore, and of course its even cheaper and crummier.
Being a real artist or craftsman, and being self employed and self motivated in doing so, is a disease which you either have or you dont. The people who succeed at this are driven, maniacial, and never take no for an answer. They work endless hours, are constantly thinking up new designs and ideas, and will sit at craft shows, cold call stores, badger gallery owners, shamelessly hustle friends, co-workers, relatives and strangers, and try to get their children to shill for them as well. If you arent already doing all this and more, there is no way you could make any money selling arty stuff. In fact, you must first resign yourself to spending years working two jobs to subsidise selling arty stuff at a loss.
It doesnt sound like this is you.
I know some of the most amazing craftsmen and artists in the country- people who routinely craft stuff that the average person is completely convinced nobody has known how to make for 100 years. And everyone of them is a stone cold madman, or woman. They are driven people who would gladly pay to do what they do, but because they have been doing it with such fanaticism for so long, they actually get so good at it that people pay them. But there is no class you can take to learn this- you gotta be born with it.
A good example would be the amazing Rivett and his minature roller skates- if you asked, "is there a market for perfectly made minature roller skates?" most sane people would say no, and yet Rivett sells em out in advance.