Spies Like Us makes Austin Powers cheaper?

I just noticed that the Austin Powers collection has some odd pricing on Amazon. The Blu-Ray edition of the Austin Powers series is $20.49 right now. The regular DVD version is $10.99. However, the collection of the first three Austin Powers moves plus Spies Like Us (no, I have no idea why) is $9.99. So the studio will effectively pay you $1 if you're buying the Austin Powers movies to also watch Spies Like Us. Interesting...