Is there something that could be the basis for bitcoin numizmatics? Maybe some palindrome hash or something?
There were two threads related to this:
A wallet.dat with bitcoins generated early, never spent, and no transactions other than the coins generated would be valuable.
Assuming you didn't mine it yourself then it would also be extremely risky to own as you would not really know if the party that you bought the .dat from didn't save a duplicate and wouldn't ever spend your collectible asset.
The next best, I suppose would be an early generation with just a single spend, from the original generation to your current wallet.
Thare are special generated coins: Obviously, the genesis block but also the generated bitcoins from blocks at the milestones 10, 100, 1000, 1,000,000, 5,000,000, and then the blocks at certain difficulty jumps might be valued, etc. Who knows.
Another angle might be if the spend was from a bitcoin that had some notable history. For instance, the first coin received by a wallet running on an Android phone, for instance.