I had a chance to audition the microphones in question, and they sound decent, and the workmanship was above what I expected... till I saw the price tag. 4 amplifiers and 10 capsules is a lot of gear, no question, and the concept if brilliant - most home recordists seldom use more than a couple microphones at a time, so this kit provides a lot of horsepower.
However, the price seems awfully steep. As has already been pointed out, one can buy a couple really good SDCs and a couple really good LDCs for $3K. You could also buy an outstanding pair of SDCs, or one LDC for that same cash.
To my ears (everyone hears the world differently) the Neuman KM-184 is not in the same league as the KM-84, or the Schoeps Collette series (if you audition the Schoeps be sure to audition the MK-41 hyper cardiod capsule - that thing is absolute magic!!)
The Shure KSM series is a great deal, they should probably be charging more for them... but I'm glad they don't.
The AKG C-451 is right up there with the KM-84 as a classic. The AKG C-414 is one you really need to listen to, some folks love them, I'm not one of them...
As far as how to buy... it isn't as easy as it once was with the dearth of local pro-audio shops. My recommendation (make that strong recommendation) is visit a couple local studios, offer to buy an hour or two, but often they'll let you audition their microphone locker for free. Spend some time with lots of different microphones, see what you like. Then check out the usual suspects...