DriveThruRPG has posted lists of estimated costs, which you can find here:
Shipping costs: http://support.drivethrurpg.com/hc/en-us/articles/209936893-Estimated-Shipping-Costs-For-Printed-Products
Print costs: http://www.drivethrurpg.com/pub_pod_cost.php
We'll be printing Large Standard Color books. At Retrocausality's original size of 64 pages, this should come out to approximately:
Softcover: US$4 / £3.04
Hardcover: US$9.17 / £6.34
Overall, the total costs should come out to less than what it will cost to get the game from DriveThruRPG later. Page size might change a little depending on layout, but not a lot.