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Sounds like a great idea! However, I think to do exactly what you need will require the use of a custom module, as in hire an XOOPS developer to build the module specifically to your needs. Others might have ideas of how this could be achieved with modules that already exit, but I don't know of any.
I think a module like this could have widespread use as it could be used for a lot more than just selling music. If you were to consider releasing it as a public module, it might be worth specing out the module then contacting a developer for a quote, and then start a pledge thread asking for people to help out with the costs.
I've just gone through a very similar process with a module I've had developed. I didn't get much response from my pledge thread, so I went ahead and had the module developed anyway and then set a donation target that had to be met before the module would be released publicly. Some brand this method as ransomware, which isn't exactly true as what we were asking for in donations was only a fraction of what the module cost to develop, but that's another story. Point being that it worked, and we recieved enough donations to ease the cost burden enough to warrant a public release. A module like this I'd say would cost at least $500US to develop, so unless you're made of money it might be a route worth considering if you think developing a module is worthwhile.