After recently updating Dave McCurdy’s Bachmann Annie, I have an Aristo-Craft accessory board (ART-54950) for a 27 MHz on-board receiver, and a Sierra sound adapter board (312036) for sale, $20 for both items. Among other things, the Sierra adapter board powers the receiver through a 6-volt voltage regulator which eliminates the need for the 6-volt battery pack.
For more information on the Aristo-Craft 27 accessory board just click on the link to read the 27 MHz on-board receiver article on George Schreyer’s web site. http://www.girr.org/girr/tips/tips5/5490_tips.html The small box postage for an American buyer from Ogdensburg, NY would be $5.35, unless you want to meet at the ECLSTS.