I heavily disagree on that idea that putting your QR Code as a private key on a coin which prone to exposure which leads to a hacked wallet.
That kind of stuff was really cool but I think there is a guarantee of safeties with your private key. However, there is stuff like that in this section.
Just go to, Bitcoin Forum > Economy > Marketplace > Goods >
Collectibles. They are all trusted there who's dealing collectibles souvenirs.
I recently bid a bitcoin coin souvenir but not having a QR code as what OP stated above.
