I have a Facebook business account that I'll be selling items from.

I have a Facebook business account that I'll be selling items from. Do you have a form that will work in their format?

Hello Tim,

You can create a form at JotForm and then get form direct link to be shared in Facebook. Also, if you have a FB page, you can add a form to it. 

Please review the following links at your convenience:

How-to-Create-Your-First-Web-Form

Where-to-Find-My-Form-URL

https://www.jotform.com/blog/facebook-page-form/