cavelamb himself wrote:

Title say it all.

I'm past the point that I can chomp parts with a chop saw and grind/file
a smooth edge.

Some of these parts have interior curves that make that impossible to
any real degree. Even with my foolish stubborn streak!

So?

Would someone recommend a small and relatively inexpensive plasma cutter
that can handle up to 1/8" stainless?

I think the Hypertherm Powermax line is the standard recommendation
these days. Check their site to see which will do the job. I know my
Powermax 1000 would certainly do it.