I'd also like to see someone with knowledge weigh in. I find it unthinkable that Apple would give more than a 5-10% margin on those gift cards. Retail stores love them despite the small cut because they're pure profit on the books: there's no inventory since they have no value until sold. I think they also get favorable terms on the transfer of cash from the sale of the gift card.
This also shows where retailers can be confusing (to me): it takes labor to ship, display, and activate those cards (activation can be a huge pain) but that's all considered fixed overhead I suppose.
Unless Apple regularly sell giftcards to retailers at significant discount, there's more than 50-10% markup.
My sole means of paying for iTunes purchases is via giftcards because they can always be obtained for a discount of between 20-25% if you look. A retailer here was recently offering them at buy 2 get 1 free, or 33% discount.
This also shows where retailers can be confusing (to me): it takes labor to ship, display, and activate those cards (activation can be a huge pain) but that's all considered fixed overhead I suppose.