It wasn't a limited run or anything, it's just that it's now out of print and since Apple launched the iMac, Apple have became the standard of innovative, industry leading product design also its brand has become more recognised outside of that of the computer and design worlds and this has affected it's price and thus desirability.
Surprsingly it wasn't that expensive when it was in print, only in the £30 price bracket if memory serves. I saw a copy in Zwemmers on Charring Cross road, not all that long ago. (year or so).
If you're lucky, you might track down a copy in a bookstore, especially outside of the capital, where demand would be lower.
I'd love for the book to be reprinted, but with the post '98 design work, that would be an amazing insight into Apples IPD output turn around since Jobs began working with Ive on the iMac etc.
If the library copy is in good nick, and it's only be taken out once in X years, then I'd try and buy it from them. 😉