The ideas here are good, but there is one reason why they wouldn't work. If the search option were suddenly available for, say, $10, I guarantee that I would be deluged by people who paid $35 when all they wanted was the search, and who felt they had been "cheated" in some way. While, of course, I wouldn't refund anything in that circumstance, it would cause a lot of ill feeling.
I agree with BardStephenFox on the issue. Look on it as a gaming purchase, much like a book. Decide for yourself whether you think it's worth the $35. If you don't think it's worth it, there's no pressure; unlike an RPG book, you are in the unique position of choosing not to pay for it. Whether that's because you can't afford it, or because you feel you don't get the same value as, say, Book of Exalted Deeds, or some other reason, nobody will hold it against you or think any worse of you.
It's kind of like if WotC gave away BoED and said "Hey, pay us if you want to; if not, no sweat!" Perhaps by paying them, they sent you a new copy with an index which the free copy lacked, but they certainly didn't stop you from having the free copy, and didn't mind in the slightest if you chose to go with that version.