I'm right with you on a loss of enthusiasm. The real solution is that Lionel and MTH should try harder to get the mechanical part right (especially gearboxes and gear ratios for slow-speed operation.) They could sell a version of their locos without electronics for a lot less money, and let us install our system of choice.
If your loco is still in good condition mechanically, you could think about replacing the electronics with a Blunami 4400, or THIS:
RailPro locomotive module with sound
To use either, you'll need a "helper" circuit that converts track power to constant, smoothed DC. But that still comes out about $100 cheaper than an ERR Cruise Commander and RailSounds. Of course you'll \need to buy a RailPro remote, but that's a one-time purchase. If you have two or three locos that fail and convert them all to RailPro, you'll come out ahead.
CVP Products (AirWire) makes a similar decoder, but AirWire's requires a separate sound module which would end up costing as much as ERR/RailSounds. AirWire and RailPro are both R/C direct to the loco (there's no command base.) Both have a physical remote. With the helper circuit, you could run these on any layout right alongside TMCC, Legacy, or DCS. Some folks love Blunami, but I don't want to run my trains with a cell phone. To my way of thinking these options are just as good or better; I can't understand why no one on the Forum has tried them or commented on them.