.... had a quote of $650 for painting of the top and bottom of the topbox.
Initial quote to paint the red LH pannier (getting from STroppy) to match the missing black pannier was $500, a second quote was $300. Perhaps I'll get what I pay for, but as the second quote is from a repairer that does quite a bit of work for Council (that I work for), I'm reasonably confident.
IMHO, $650 is a bit excessive, getting another quote night be prudent.