I'm working on a device that illuminates a signal LED when a button on a remote is pressed. I have a working prototype based on a pre-fabricated board I bought on Amazon (see here), and it's nice! But now I'm toying with the idea of producing these on a larger scale, and looking for a less expensive solution.
The thing I keep running into is that every system like this one is relay-based, and for the life of me I can't figure out why. Couldn't the same thing be achieved with a transistor? Is there a generally less-expensive solution out there I should be looking for?
Spoiler alert: I'm very new to electronics design, please explain like I'm five.