Back in 'the day' when you wanted music you had to go down to the record store. Opening up iTunes or pulling out your Zune or searching The Pirate Bay weren't options. When you got to the record store, you had a few options. If you didn't want to spend a bunch of money on a whole album, you could always pick up a couple of 45s. A 45 was a smaller record that only held two songs, an A side and a B side.

These days we don't use many records anymore. Audiophiles still do, and real connoisseurs of sound swear by them, but for the most part we've gone digital with our music. The fact that the technology is obsolete doesn't mean that the marketing ideas are. Apple has swung back around to the idea of selling songs in pairs, and now they're offering special D45 (digital 45) value packs.

Prices of D45s will vary between $1.49 and $1.99. As a general rule you'll save between $.50 and $.75 when you buy a D45 instead of purchasing the song's separately.