You can definitely purchase a one-time box! To do so, you can just send yourself a gift.
For details on how to purchase a gift, please see our How To Order an OwlCrte Gift article.
If you purchase a gift for yourself, using your own email address in the recipient field, you will receive two order notifications/numbers. One for the Gift Giver order (essentially, your receipt) and one for the Gift Receiver Order (the gift itself). The latter will have a $0.00 charge.
If you have any questions, please email firstname.lastname@example.org