I would say that even if you already own a couple of the elements, Komplete is still worth it. Especially if you go for Ultimate and get it on sale (which I did with 8, then upgraded to 9 Ultimate). I don't know what the total full retail price of everything would be but it's high. Even if you have say Massive and FM, there's still the full versions of Kontakt and Reaktor, which are HUGE programs (and don't forget that having the full Reaktor grants you access to the full Reaktor User library and thus 1000's of unique synths, effects, drum machines etc).
Even forgetting about the big standalone synths, there are synths which run in Reaktor like Skanner, Monark and Razor, all of which are awesome (not sure which come with Ultimate though). And the libraries are worth the price of Komplete in themselves. Not to mention the extra effects you get for Guitar Rig, and the vintage compressors and EQ's you get with Ultimate. I really don't know where I'd be without it. Like Waves bundles, you get a HUGE bang for your buck (especially if like me you got them on sale).
I'll upgrade to 10 when they have a blowout.