In that case what I would do is:
A) Wait until the books are back in print and buy them then.
or
B) Figure out how to get the stuff you want at the price you want and get a second Kickstarter account to do so.
But NerfTW is quite right. This
isn't a storefront. As I said many pages ago,:
So if it isn't worth it to you, don't feel pressured to get it. Just get what you
are comfortable with. And if that is some books now and some books later? Well, that's still some money to the drive, inn't?