went poking around one of my fav hobby shops and what to my wonder did I find. A "BEEP factory".
not really a factory, but he had lots of BEEPS.
$49.99 and he had BEEP dummys for 24.99
with a neat alternative, the BEEP dummys were originally powered but the boards were burned up so he took the guts out and the center pick up rollers off to make them dummys. He still has the pick up rollers and motors, so I guess you could put them back and install a rectifier and have them powered in one direction.
he also has BEEP shells on flat cars. didn't see the price for those.
he has many many road names.
contact Kevin Besser at Besser's Whistle stop
Baldwinsville, NY.
http://www.besserswhistlestop.com/