Something to consider if you started a digital book archiving business. Your clients would probably want their original books intact after digitizing. You'd probably need a device like Google uses that turns pages, rather than the ScanSnap approach. Might be justifiable to invest in building such a device since you'd like to digitize (and preserve) your own sizable collection. If the price is < buying a digital copy (if it even exists) of all your books, then build. Get a few clients, and recoup the costs.

I'm sure there's copyright issues to deal with as soon as money changes hands too. Probably something you could work around though.

Perhaps you could simply rent the machine out by the hour. Have your client sign a liability waver, and be on your way. :)

Or heck, make it work like a coin-op copying machine.