Great summary James!
I was hoping the OP would let us know what kind of trolley he has or is considering. It's such a difference if command-control is in play, or if trolley uses a traditional AC E-unit if lights/sounds at the timed stops is of interest.
I like how you included price info. To that end, I looked up the Dallee 682 that Mike refers to above.
It also occurs to me that with low-power LED technology, it would not be a stretch to add a capacitor or similar simple circuit to keep the lights on at station stops even if there's no power on the track itself. Or for more play value maybe the LED circuit charges while running keeping cabin dark...but then lights turn on only when unloading/loading at the station! So many possibilities!