On the contrary, the KBU-300 is still available on amazon. I got mine for free since I placed in my review that they are using Panasonic drive mechanisms. Well, when Panasonic stops manufacturing their 4K Blu-ray line, then there will be no more drive mechanisms being built. Krovatar claims that have taken heavy stock in this part.
It's impressive for such a compact unit. However, I still went out and purchased the Panasonic DP-820K for $549.00. I just checked, in the past week, they have upped on the price. Now it is in the $649 range. Absolutely not worth it when you consider the unreliable disc tray that is temperamental. This unit came out in June 9, 2019. Panasonic is milking this for every Nickle. Back in 2019, this unit retailed for $350.00. Talk about a mark up!