hobbyDB's system architecture is fully based on Restful APIs.  Database Items, Estimated Values, Subjects and Items for Sale are all accessible through the API. Let us know if you are interested in exploring co-operation and using the API. Please provide us with a good overview of your project.  As we only have a small team and a lot of work to do we would ask you how this helps to advance our aim to document 100 Billion Collectibles (such as traffic or income).