I'd say skip the Blofeld. It's kind of nice but a bit abrasive to use as your "bright" synth given the sort of budget you appear to have. Also Waldorf are bringing out a softsynth version of it soon anyway.
Have you given any thought to some nice hardware effects? The best distortions, reverbs, compressors, etc, are all hardware units imho - to my ears they utterly blow their software counterparts out of the water.
Let me attempt to pique your interest.
Here are three of my lusted-after units... so far I only have the Vulture.
Thermionic Culture Vulture (Distortion)
Bricasti M7 (Reverb)
Ridge Farm Boiler (Compressor)
If you're really set on buying a third synth, and you want something bright to complement the thundering LP and soft/warm/dark virus, personally I'd try and save up for a Voyager. It will do bright/cutting fine and it's very versatile, not to mention incredibly sexy. If I could own any three synths, those would be it.
-Annikk