Can I create a Buy-it-now listings for a specific person?

[californiagirlsvintage]

What's the policy, if any, on listing items specifically for one person, and that person only?

Several times, prospective customers have messaged me to buy items not yet listed (by asking if I had more) and we have agreed on a price for the lot, but I don't want to cut out eBay since I wouldn't have the sale if not for this venue.

The first time this happened, I just wrote the buyers eBay ID in the title, but a friend said she thought it wasn't allowed. Too late for that one, but I want to do it again, but not if it's against the rules.

Is there a way to write a listing that includes a specific buyers name, or omits everyone else? Or is this not allowed at all?

Thanks