This is how I figure it...
From a pint you could plate literally hundreds of small items, if
you take care to avoid waste. For this reason I use a plastic
container so that I tap off as much solution from the piece as I can
before rinse. Same thing for the anode. Don't you just love watching
your rhodium bottle get lower and lower?
Most of the value (as I perceive it) is in the prep work. Be it
repair or a new piece, careful and thorough polishing and stop-off
(if needed) is what results in a great finish.
So typically I don't have a 'rhodium charge' per se. But if I were
handed a bunch of prepped pieces (say from a jeweler friend) to
rhodium I would probably charge $10 per. If rhodium became a regular
line of business I would certainly look much more closely at the
economics of it. But for now, the way I work, I get enough for
repairs and/or new pieces to just absorb the cost of the
solution.(ex. $100,000 worth of white gold work with a rhodium cost
of $400, I could live with that) My equipment I've had for so long
that its cost doesn't figure in anymore.
All that being said, I can see where someone who is setting up for
rhodium should probably charge in the area of $25 retail plus
polishing. I would shoot for recovering my investment within one
year. So it really depends on the volume of pieces one does.