At any time during the Kickstarter project you can add the price for the additional items you want to your contribution, just keep your desired contribution level selected and add the additional funds. You can add to your contribution level as much as you want and as often as you want during the event. After the Kickstarter project ends (and closer to when the items actually ship) we’ll send a “Survey” form where you can tell us EXACTLY what you want for the amount of money you have already sent.
Example: You signed up for the $54 Squad Commander level. We "unlock" several stretch goals and you want to add 2 (two) of them to your order at $15 each. So just increase your original contribution by $30 and then let us know what you want for the $30 in the kickstarter survey (which will be sent after the event ends and closer to the actual shipping date).