Headlights won't come on

I've been having an issue I can't track down (not being very knowledgeable
beyond basic repairs).

Initially, the 'battery', 'brake' and 'ABS' indicator lights have been turning on
and off... when they come ON, my dash and headlights all get brighter.  
When those indicators turn off, everything goes back to normal.

This morning, I had my high beams on when this happened, and after a
second my headlights turned off completely at the same time, and will not
turn back on.  Now my high beam indicator is lit, and stay lit.  Sometimes
when the indicator lights turn on, the speakers make an electrical cracking
sound and then go silent, but the sound returns as soon as those lights go
off.

Are there any things I should check before I spend $250 at the dealership to
have them look for a problem in my $1300 car?

The battery is new (this happened with the old battery as well as with the
new one) and the alternator tests perfectly... it's functioning correctly.  What
else might boost the electrical power through the car to make this happen?

FYI, I have a misfire in cylinder 3 that I haven't repaired yet... new plugs and
wires next week.  I don't think they've ever been replaced as I know the
original owner (grandpa).