Media you own that has become harder to find copies of

Ratatoing
I got my copy some years ago for only a dollar. Now there’s only a few listings on eBay for the exact type of copy I have. I don’t think they manufacture them anymore since the last time I saw them for sale was like 5 years ago.

I have all the gen IV pokemon ds games. Not uncommon, but they're expensive as hell nowadays.

I have all them too. In the UK there are listings for Platinum on eBay for just the box, loose cart or the box and cart and people are asking anywhere between £28 and over £100

I don't have any Video Brinquedo DVD's but I find them interesting. I still have lots of VHS. This is the one I got most recently:
drive.google.com/file/d/1HfTMRZf3SUZpiYMEbIrZ9jJY0zOe30jc/view?usp=share_link

Some old Serbian Peppa pig books from 2010s that i have are hard to find. There's no listing for some of them online or they get sold out quickly.

No, I don't think any Serbian books are on there. I don't know how to digitise them and they have some coloring in them. I've uploaded a video where i show them so I don't really think it's lost. 

1. A DVD about the Tennessee Basketball 2006-2007 season that I assume was exclusively sold in this particular state, likely with very few copies ever being printed. Got it from a local store for relatively cheap all things considered.
2. Star Control for the Sega Genesis, which was one of Accolade's unlicensed Genesis games.
3. Tiny Tank for the PS1(Rarity Guide says it's on 68% in terms of rarity)
4. The original NTSC-U print run of Asteroids on PS1(the Greatest Hits version seems to be easier to find)
5. Arkanoid on the NES(76% rare!?)
6. Sphinx And the Cursed Mummy on PS2(54% rare? More than halfway rare? Huh.)
7. Pac-Man World 2 on PS2
8. Sprint Cars 2: Showdown At Eldora on PS2
9. The original NTSC-U print run of Ty 1 on PS2
10. King of Fighters 2000/2001 combo pack on PS2(JEEZ HOW MANY SEEMINGLY RARE PS2 GAMES DO I HAVE!?!?)
11. Capcom Classics Collection Vol.1 on PS2
12. Mega Man X Collection on PS2
13. 3 PS2 NTSC-U copy Armored Core games(2, Another Age & Silent Line)
14. Destroy All Humans! on PS2
15. Final Fantasy XI on PS2
16. The greatest hits run of Baldur's Gate: Dark Alliance on PS2(not as rare as the original print run)
17. Baldur's Gate: Dark Alliance II on PS2(84% rare!?!? I don't believe it either!)
18. Hitman: Contracts on PS2
19. The original NTSC-U print run of Lord of the Rings: Return of the King on PS2
20. The greatest hits print run of The Godfather on PS2 maybe? IDK, Rarity Guide doesn't list that version unfortunately.
21. Wipeout Fusion on PS2
22. Zombies Ate My Neighbors on Sega Genesis
23. Streets of Rage 1 on Sega Genesis(71% rare? Ok yeah, the retro gaming market is very messed up!)