I think wandering traders should sometimes offer to trade one music disc for a different music disc. That way, it could work a bit like a trading card game.
The discs that can be found in generated chests should be of lesser value, because they're easier to obtain. Perhaps the trader could ask for two low-value discs in exchange for one high-value disc. Alternatively, the trader could ask for a low-value disc and some emeralds in exchange for a high-value disc.
I enjoy the challenge of collecting music discs, and I think this idea would add an extra element to it. You'd still need to obtain the music discs before you can trade, and you'd have to wait until you find someone offering the trade you want. To maintain the level of challenge, maybe there could be a new music disc that can only be obtained through trades. This new disc would be rare, and of higher value than all the others.
I like this idea reckon it would work well with the other idea i had when expanding on the goat flute horn idea thats on this site. Look to the goat flute horn thread bud you might like my idea that pushes the flute idea further.