Can someone explain what is being said here in color publishing in the American Mathematical Monthly? Under "Information for Authors" at the American Mathematical Monthly, there is this statement for color charges in publishing:


  Color art will be reproduced in color in the online publication at no additional cost to the author. Color illustrations will also be considered for print publication; however, the author will be required to bear the full cost involved in color art reproduction. Please note that color reprints can only be ordered if print reproduction costs are paid. Print Rates: $900 for the first page of color; $450 per page for the next three pages of color. A custom quote will be provided for articles with more than four pages of color. Art not supplied at a minimum of 300 dpi will not be considered for print. Please ensure that color figures and images submitted for publication will render clearly in a black and white conversion for print.


What does this mean? Am I understanding correctly that if they decide to publish your article, then they will charge you, the author for color figures in the article? 

I also don't understand the distinction between online and print - does the author have a choice which to submit to? I don't see this information on their website.
By default, color figures will appear in color online and black and white in print. If you want them to be in color in print, you need to pay the rates they indicate. All their papers appear both in print and online, it is not that you choose one or the other. They also advice on the required quality (resolution) of the figures (regardless of color) and ask that if you use the default option the colir figures are understandable and meaningful when rendered in black and white.

Other journals have an option for slightly different figures for color and black and white, which may make things easier sometimes (for instance, in black and white you use different kinds of shading as different "colors"). It doesn't hurt to ask if this is also an option here.