I managed to pick up a copy a few years back, for about $50. Not in the best condition, either. Anyway, I would certainly pay for a decent PDF version.
As for alternatives, CP2020 has its lifepath thing, of course. And now, there is also
Interlock Unlimited, a fan-made RPG based on its fundamental system, but for a variety of genres and styles. Along similar lines, but definitely fantasy - and also quite tied into its setting - there is
Artesia, the very pretty Fuzion-based RPG (well, its charater creation system, being the relevant thing here). And, while I'm on Fuzion, there is a multi-genre lifepath document for Atomik Fuzion floating around the interwebs too. There are a number of lifepath thingies online, here and there (e.g.,
this one). Also, there's a PDF available on RPGNow / DrivethruRPG called
Background Noise (by 'Second Rat Games'). And, before I forget to mention it, Savage Worlds has
this.
That's all that comes to mind right now, other than the things previous posters have named.
Oh, one more - the
Hero Builder's Guidebook.
edit --- Here are some places that have copies:
Amazon,
Noble Knight,
eBay