I looked for parts washing solvent, and I am finding that it is a
lot
more expensive than other hydrocarbons like kerosene. I am
wondering,
why is this the case?

Any idea what is a relatively cheap way to get about 40-50 gallons
of
that stuff.

I shopped for it, and said fergeddabout it. That stuff is more than a good
single malt scotch in some cases. I ended up with a mixture of stuff,
mostly water and oxy clean, plus a little paint thinner, and other stuff
that has washed down there. But I don't use mine a lot. I really need to
take it apart, and inspect, as I noticed a good bit of corrosion when I
first got it.

I'd be interested in a good cheap all around safe cleaner, too. I ain't
spending that much for enough for my $15 yard sale 30 gal. Snap-On unit.
Sorry, I'm just cheap.

Steve