Oh wow, thank you, this is really, really helpful to know!

We're so used to the paying-in-installments piece that we must have gotten blind to the fact that people seeing it for the first time would think it's the total price.

Same thing with the delta – it's always 1 / 24 of the final price (you pay the artwork off over two years), with a minimum monthly price of $30 (for the artist's sake.) Put differently,

  if ( fullPrice / 24 ) > 30
    monthlyPrice = fullPrice / 24
  else
    monthlyPrice = 30
  end

(edited for line breaks)