nad1r,
Thank you for your feature request. The ability to create new “database fields” is in the works. There are many other features along with paid work that I must do first, so if this is a time sensitive matter for you I would look into either hacking the plugin yourself or possibly making a custom solution.
By the way, CataBlog is built upon the Custom Post Types feature in WordPress 3, and by doing so does not have its own database table. Instead CataBlog uses the built in WordPress tables to store its “fields” as meta data. I am considering the pros and cons of saving each catalog item field in its own row, or keeping them all combined in one database row.
For instance, a pro of separating each field into its own row is that you would be able to order your catalog by a custom field. The downside though, is that if you have a lot of fields, your database will start to choke. There are ways to let people pick and choose, it just takes time to write and code all these features.
Your feature will be in a future version of CataBlog, of which I cannot say when it will be released. Right now my aim is to release a stable 1.3 version that does multiple file uploads on most if not all setups and contains few or no bugs.
Also, after some thought I have decided that I should not sell customized versions of CataBlog to clients, it will create a possible conflict of interests among people who have paid for a specific feature and the public users, whom eventually will get the feature that was paid for.