Librello Publishing is a new open access publisher with a model somewhat similar to PeerJ. But while PeerJ has lifetime memberships that then allow you to submit as many papers as you want (for $299 membership and one or two papers a year for the discount classes), Librello is using annual memberships of 156 Swiss Francs. As its five journals are mostly in the social sciences this higher pricing is necessary as the average number of authors is lower. In practice this will likely amount to the submission fee which many subscription journals already charge. For example, the Energy Journal requires you to either pay USD 100 per submission or be a member of the IAEE. Assuming a 50-70% rejection rate this is still very much below the pricing of a conventional open access journal like PLoS ONE, which is only profitable because it operates on such a huge scale. However, this looks to be a totally legitimate publisher with a respectable editorial board for the Challenges in Sustainability journal.