They do, so to speak....use the wishlist feature...From their FAQ

Q: I like to add one item to my shopping cart each day over the course of months. Can I save my cart and keep coming back to it to add more items?

A: Yes, but do not add items to your cart, add items to your "Wishlist". Wishlists can be created and managed by following these instructions:

Log on to the Pinball Life web site using your log in name and password. Do not add items to your cart, add them to your "wish list". You will find the "My Wishlist" button in the "My Profile" section at the bottom of the left hand column on the front page of the Pinball Life web site. Click on "My Wishlist" and you will then be asked enter a name for your wishlist (you can have more than one wishlist at a time that way). After naming your wishlist click on "Add Wishlist". Now you can add items to your wish list instead of adding them to your cart. The "add to wishlist" link is right under the "add to cart" button on any product page. To see what you have added to your wishlist click on the "My Wishlist" link located on the right hand side of the gray bar towards the top of any page of the Pinball Life web site..... Click on "My Wishlist" and then select the wishlist's name and you will see what's on the wishlist. Individual Items can be added to your cart from your wishlist by clicking on "add to cart" from your wishlist, or the entire wish list can be added to your cart all at once by clicking "add to cart" from the wishlist title page. Once you have added something to your wishlist(s) it is there until you delete it, even if you log out.