Best way to write a plugin with custom content?

I am in the process of writing a wordpress plugin that will allow the administrator to create a list of items, each with their own page of information.

Currently, I am using a custom post type for creating new items. However, I wish to modify the page for creating new items to allow the administrator to set custom fields like price and image url. I can’t find an API to do this, and the closest I can do is manually type in the key and values for each post.

My question is, is custom post type the best way to go for this? If not, what should I do?

Thank you.