I first started looking for one, around 1998, 5 years after I rekindled my interest in coins. I finally got one in 2021 , together with the other varieties of Eliz II sixpences, in an auction. Cost, allowing for rarity and pro-rata with other coins was around £20, including commission and postage. Some years ago, on here there was a collector named Gary (D?), who only collected 20thC and who sold his collection in one go, rather than split it. I don't know who bought it, and what happened to it, but the set of 6d's I bought seemed to correlate very well with those from his collection, so maybe I got the benefit of the eventual split up?
Anyway, I'm afraid that I don't have a spare, and if my experience is anything to go by, it will take quite a time to find one. They don't turn up with dealers nor ebayers, probably because they are a bit obscure, and so it isn't easy to find one in the usual way. For the rarer 1964 variety, I found that grubbing through boot fair pots was the answer, so maybe this would work for the 1965 one. Best of luck.