If the stretch goals are met, there will be several new tiers added to the campaign. For example, alternate $30 tier with a CD set of Metroid Cinematica. There will be an assortment of packages available to give everyone more options, including an alternate $100 tier which includes a CD pack from each Cinematica album. And if the final stretch goal is met, a "Master Set" which includes all of the CDs and a vinyl print in the same package.
Kickstarter allows you to change your reward tiers, so once the new ones become available, you can switch to a new tier that you like better!