I'd be very surprised if cutting out the audio and some lighting features changed the manufacturing costs more than $6-8 or so. Given that the PS/3 diesel board can't possibly be costing more than the $40-50 ballpark, I don't see this moving the needle on purchase costs enough to justify the engineering to create it, and then the ongoing costs to support another configuration. I'll be stunned if that happens.
What would be useful is a really cheap DCS based receiver that just gives you functionality like the ERR Mini-Commander ACC board to automate rolling stock and the like. That's functionality that is totally missing from the DCS product line.
