You certainly have an advantage by owning a print shop! :) I agree that spiral bound is the best for these types of books. But spiral bound books are so difficult to sell online from a logistics standpoint.
You could use Amazon FBA. However, remember that you may need to shrink-wrap the books to make sure they don't get damaged in warehouse storage and handling. The spirals can get caught on things which will not only damage the spirals, but subsequently the pages.
There may be other options through the likes of Etsy or Shopify where you sell direct to customers. But that could mean additional cost and labor for you for ordering processing, shipping, and handling. Also, be aware of the costs of these sales platforms. Price your journal to account for any additional expenses you'll incur. Same goes for Amazon FBA.