Whip antenna for smallest PowerBook

As a 12-inch PowerBook owner, the blurb on MacMinute about QuickerTek’s new Whip Antenna for the smallest PowerBook piqued my interest. However, after looking over the product page, I’m left wondering if this wouldn’t just be something that would easily break off. It appears to be a permanent or semi-permanent installation; how does that affect my three-year AppleCare warranty? The kicker: 90 bucks. Sheesh. Fifty I could understand, but it seems a little overpriced as is.