Mainstream Comics— Dark Horse, Marvel, DC if you’re just starting out will be between $200-$300 per page. Everything is different for everyone of course, but these rates are pretty standard for the “Big Three”.
So that’s PER page— which means the average comic is 20–22 pages so your paycheck (which comes as a digital voucher deposited into your bank account now) is $4,000-$6,000 per book. If you are only able to do one book a month that means your annual income will be $48,000-$72,000.
Obviously if you can do more than one book a month your income increases. It also rises as you make a name for yourself or your work sells particularly well.
Keep in mind the number of comic artists on salary is extremely small. Jose Garcia Lopez at DC Comics and John Romita Sr at Marvel come to mind. 99% of the artists working today are freelancers, which means you pay your own taxes either quarterly or in a big fat check at the end of the year.
Smaller companies pay $100-$150 per page and both big and small companies offer royalties over a certain number of copies sold as well as for reprints and collections of your work.
As an artist, if you work traditionally you can also sell your original art pages for around $100 – $1000 a page depending on the content of the page (and that’s for mainstream comics again).
The vast majority of artists today work digitally, so there is no original art in those cases, bringing up the prices of the art that does exist.