You're the DM and the creation requirements of any magical item is ultimately up to you (to answer "can choir be used to enchant items"). I think it's great you're willing to work with your player on this. Does he want any of the actual mechanical benefits of Choir from this, or does he just want a magic item that functions as a phonograph? If the latter, I'd certainly use the suggestion below, perhaps even lowering the price.

Ok, so it's a 4th level bard spell, minimum 10th level. I'd look at the rules for wand crafting. The price for crafting a wand of choir would be around 15,000 GP. Keep in mind, wands are limited use items, so basing it off this, you may want to raise the price. However, there are items with significantly more benefit than it seems your player will receive that cost only a few thousand more, so I'd keep it under 20,000 GP