RE: Battery/DCC Cost Question
The biggest issue I find with converting to battery R/C (or DCC for that matter) is getting into the loco and figuring out what goes where to install the electronics. Almost every loco is different. While "plug-and-play" interfaces have made things a bit easier, there are still some ideosynchracies that get in the way of things being truly universal in how to go. Some recommend gutting everything and starting from scratch (whcih is certainly a viable option in some locos), but other locos--if you want to take advantage of some of the on-board electronics they have for lights, chuff triggers, etc., it's not quite so clear-cut.
My other thought as it comes to battery R/C systems is not to get so hung up on trying to pick one specific system. In all likelihood, you're probably going to want a second transmitter at some point, for multiple operators, redundancy, or whatever. Why not make the second transmitter you buy a second system? Each system on the market has different strong and weak points, which can be exploited to fit each individual installation. That, and if you've got multiple systems, one supplier can hit a dry spell for whatever reason and not leave you hanging.