John, Your comment is right on as to the expense of conversion. Comparing the embedded factory bells and whistles to an $XXX expense per engine to go battery RC, can be a real stumbling block.
I know that as a DC operator, early on I did consider DCC. At the time I had 63 engines and the math was overwhelming.
However, The wiring on my way-to-large RR was equally overwhelming in how it was dragging on. That's when I got my first R/C.
Battery R/C comes in may iterations. From a basic $99.00 Piko system to $300+ bells and whistles set up. Our local R/C plane store will do an locomotive complete with system, controls , battery installed for about $125.
Getting older, tired & sore with diminished ambition, The R/C was the answer for me. I still have an array of PS-2 & 3 equipped locos which are enjoyable, but the satisfaction of not having to wire the peninsula additions is a welcome trade off.
Plus I got rid of several excess locomotives to off set the conversions.