Public read access, renter pays for download bandwidth?

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I think this question has been touched on in various topics in this forum but I'm still not clear on it. Is it currently possible to distribute .sia files, which when used to download content, charge from the renter contract and do not require the downloading client to pay? I'm unable to find a resource describing download channels, if you can point me in the right direction it would be much appreciated! It seems limiting to require all clients to be 'pre-stocked' with Siacoin, but maybe I'm misunderstanding.