I think you start by getting all of your data into a database. You are going to have to figure out what fields are necessary for each product, then create the basic database structure.
Then you can run dataAssist to create the insert/update/search pages and start entering the product data. I'd only enter in a couple until you have tested and make sure everything works the way you want. Then you will have a copy/paste exercise to get everything inserted into the database so you can update your front end catalog to be dynamic.