Hi everyone. I've fallen down the HarperCollins Deluxe edition slippery slope

In 2016 I picked up The Hobbit Facsimile edition and recently got it out and re-read it. I love the quality of the book and slipcase, and one thing led to another and I'm out to collect some of the HarperCollins Deluxe editions. I have Beren and Luthien as well as Fall of Gondolin. The Children of Hurin and Silmarillion are at the top of my list, and I realize that The Hobbit and LoTR won't be far along after that.

So now I'm wondering, is it possible to still find the limit 4-volume set? I've checked the usual places and haven't come up with anything. Do these still pop up from time to time? If I'm patient can I get it?

Looking forward to hearing any insight, perspectives or opinions on this or even my crazy new goal of collecting these