I think you could use Numbers for your database. It doesn't work well as a container for graphics though. I would suggest that you keep your scanned artwork on a web service such as Dropbox so that you can record the URL in Numbers and keep the actual graphics storage on a server. The reason for this is that Numbers can't reference a file stored locally, and Numbers becomes sluggish if the graphics are stored within the document.
When you build a database in Numbers, each row is a "record", or separate item, and each column is an particular attribute; your keywords, comments, publication date, composer, illustrator, publisher, value, condition and purchase date.