Accomplished_Drop264

I have been considering Train Automation but the colour and distance sensors are now not available from Lego and so have become really expensive. Does anyone know of or have any experience of aftermarket sensors? Thanks in advance ☺️

After much head scratching I've decided to as you guys and girls for help. I'm trying to run 2 powered up trains from the app at the same time but, every time I switch trains the other stops. Are my only options either 2 phones running 2 apps or, a phone and a controller or 2 controllers? Or am I missing a trick? Thanks in advance ☺️