How reasonable would it be to assume that there are those in Golarion who could record performances (bardic or otherwise) and sell them to the public? The Clockwork Spy's record audio ability could easily record a good length of audio. While the recorded gemstones in and out might be a bit difficult, they could possibly be sold at profit. There's probably someone who wants to hear music multiple times and all. And as far as I can tell, there aren't many items that allow for musical recording and playback. This could be the next big thing sweeping the world of Golarion as we know it.
But the cost of each 'record' would be 50 gp. That is actually quite exuberant, isn't it? Most people do not make more than 1 sp per day. That is worth more than the average yearly wage. And this is all before mark up for the music and not to mention the cost of the playing device (probably much smaller than the 750 crafting cost for the construct since it shouldn't move..but still)
Of course, if you want to market things to rich nobles, then go ahead. I assume most magical items were commissioned by them anyway, so why not make a fad and a tidy profit? But even then, they could easily hire a decent bard for a year with that kind of price. Maybe even a whole band.
The crafting cost seems to be initial capital for the publishers, seeing as the gem doesn't need specific hardware to play.
It could also be used for speeches of merit. Something a king would proclaim and send "records" of throughout his domain. Besides, maybe there are enough musical enthusiasts who are well to do enough to enjoy particular sets in their own time.