What's the business model, you bear the costs of recording audio and take a share (or all) of the profits, or the writer (LW in this case) bears the costs and you split the profits? Most people seem fine with CC-BY, you could tweak the split or the fee for the odd person that wants CC-BY-SA until it's profitable again (or eat part of the cost to keep a client happy, if LW brings in enough business otherwise.