Ecnerwal writes:

At the risk of beating a dead horse, order some from Zenni or another
inexpensive on-line optical store - or patronize your local
higher-priced shop. I don't think they even start charging extra until
more than 6 diopters, which is getting into whacky
short-working-distance land unless you are starting from farsighted.

One note on this is that while I've been able to find cheap reading
glasses easily (I'm wearing a pair of +1.25's from Wal-Mart as I type
this), and I've been able to find cheap bifocal safety glasses, the
only way I was able to find a pair of constant-correction, ANSI Z87.1
safety glasses was to have my optometrist write me a prescription for
them and pay a little over $50. I'm new to the reading glasses world
(I'm only 50, so I've only been wearing them for a year), but so far
I've found reading glasses OK and half-glasses OK, but bifocals pretty
consistently require me to hold my head at a really weird angle to
look at anything close up (before somebody points out the obvious
apparent inconsistency here, no my half-glasses don't put the lens
anywhere near where any bifocals I've tried put the correcting part --
the half-glasses put it much, much higher, and are much more comfortable).

I didn't spend much time looking at Zenni, but neither of the magic
phrases "safety glasses" nor "Z87.1" seem to appear in the
descriptions of their prescription goggles.