My current plan, though this may be subject to change, is that the basic price of the Kickstarter book copy will be $18 USD; itch.io allows me to send emails out to people who own IaM, and Kickstarter allows me to generate links for specific otherwise-hidden pledge tiers, so I have a Kickstarter pledge tier set up that allows people who bought IaM during the draft phase to pledge for the difference between the current draft price (at $10 USD) and the final book price - the link to which I'll be emailing current owners. That way, anyone who buys the book now won't end up paying any more for the final book than people who back the Kickstarter, at a baseline "I just want the book" tier.
Everything will be handled through this page on itch.io even when the Kickstarter completes - I'll just be changing the minimum price and delisting the old versions, as standard.
I hope this answers your question!