Sure, you can't sell that disappointed visitor anything because you've sold it all. But that doesn't mean people aren't still interested in that particular wine. If they enjoyed the bottle, they might be trying to understand just what it is that made it enjoyable for them. And you can always offer a link to the current, in-stock vintage (which might lead to a sale). Most importantly, they are a visitor to your Web Site, which means you want to help them as much as possible.
Best practice? You should have one page on your Web site which lists every wine you've ever produced (ideally, sortable by vintage, varietal, and name). Each line in the list links to the original product page for that wine. Nothing fancy.
OK, so you haven't done that in the past. Don't cry over spilt milk, just create that listing page today! When a wine is sold out, change the "Add to Cart" button to a "Sold Out" with a link to the current vintage.
For extra credit, add something like the excellent How's It Drinking? chart from Tablas Creek, plus any additional tasting notes as you sample your library bottles of the wine over time.
And, if you really want to impress your visitor, tell them where they can still find a bottle. Done correctly, this will also allow you to stay in touch with someone who was interested enough in your wine to try and find out more about it.
Why put so much effort into a wine that you won't realize another dollar from? Because you may only have one shot to turn that searcher into a future customer.
As a side benefit, the additional page can (potentially) help your site rank better on search engines.