What does "going broke" mean to you? Depending on context you can spend $600
and get a lot, or $20,000 and get a little.

I agree that an HSI is very nice to have, but it really only confers a
significant advantage during the approach phase. Admittedly this is a very
good time to gain an advantage, but for similar amounts of money ($5-10k)
you can add any of datalink weather, TIS, or pseudo-TAWS to a GNS-430.
Weather would be my first choice, as it helps in both IFR and VFR, and
contributes to the overall success of the flight, and not merely making an
approach or hold entry easier.

I spent 2 hours banging around in some pretty thick clag in my 172, equipped
with two nav/coms, an M1 loran, and a flaky ADF. My wish list would be,
roughly, a moving-map GPS, weather, and an autopilot, in that order. I
normally only fly low IFR with my instructor, otherwise I'd put the
autopilot up higher. If I had to choose between the 430 and 480, I'd go with
the 480 because it has airways support, and airways rule the Northeast. But
frankly either one would be great.

As to the ADF, I'd keep it so long as it works and doesn't take up needed
space. But I wouldn't put another penny into it.

-cwk.