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If the "Gift this album" option isn't available, you could purchase an iTunes Gift Card or Certificate instead. The following links will help you with this:
iTunes Gift Cards
iTunes Gift Cards are the perfect way to give the gift of entertainment. You can buy them in different styles and denominations from Apple and from thousands of other retailers. And no matter which card you give, recipients can redeem it for whatever they want to buy — songs, movies, TV shows, apps, games, books, and more.
Buy from the Apple Online Store
I'm sure your recipient will appreciate your thoughtfulness.
I had this same problem trying to buy GoodReader for some iPads here at work. The gift option was fine for iWork, but had disappeared for GoodReader. This is especially odd because we've done this before with this app. Why would the option not be there??
(FWIW, the OP asked about an App, not an Album)