Are you invoicing them for it directly, or do you want it visible to only them on the website? And what is "the website"? What are you using for a commerce site?
What I would like to do is have a way to sell a special ticket through Square that I don't have to put up on the redirect site. Like a special link where a group can use that the world can't see.
I would give Checkout Links a try. It allows you to create a pay link for an item and customers will be taken to a simple checkout page to make a purchase.
