One thing that hasn't been discussed much is this: What will be the real capabilities of your airplane? I alluded to this in suggesting that I kept my own avionics relatively simple, because I fly a relatively simple airplane with relatively low capabilities in the IFR environment--yes, I can fly in the clouds, and yes I can make an approach to minimums, but no, I can't fly in icing or get above thunderstorms, so why have the equipment that would allow a much more capable airplane do those things? There is a really bad tendency, fostered by fancy technology, to pack relatively simple airplanes with much more "stuff" than can ever be used effectively. And all of that stuff is expensive! Why in the world any 172 needs a full Garmin G1000 suite makes little sense to me, for instance. On the other hand, a T210 or SR22 with FIKI approval can use that stuff pretty effectively.
So before shelling out lots of bucks for fancy avionics, that's an important question to answer: What will be the capabilities of your airplane? If no matter what qualifications you have, your airplane will be essentially a VFR only airplane, your avionics needs are a lot different from an airplane that can be comfortably flown in the system, in many different kinds of weather.
Cary