I think limiting splatbooks has perverse effects. It helps out characters whose abilities are self-contained in a single book or two, and hurts those builds who are, coincidentally, spread out all over the place. A side effect is that it also hurts spellcasters less (I know we're all shocked) -- nearly everything they need is in the Spell Compendium, PHB, and maybe another book or two. Other abilities are often essentially randomly distributed among books.
One solution is to have a decent gentleman's agreement about how good your characters need to be. Then, you know you can stop diving after you've reached that point. I know I always have a temptation for more diving, often of books I already know well, to find some fun and interesting options, but I find that having a decent sense of when to "stop" helps whittle things down a lot.
P.S.: I use digital copies for all my books, even the ones I already own. There are also handy compendiums out there that compile nearly every feat, spell, or item in one source. They're searchable, and I find that very handy. Part of me suspects that the iPad was secretly designed for D&D, since that's probably where it's made the biggest impact in my life.