In regard to the "cheapness" of COAL, look, you're not getting a light-up keyboard. It's 1986, and game show games with light-up functions are either the Quizzard in $OTC or those tiny lights running off a 9-volt in Electric Jeopardy, and both of those are toward the luxury end of the board game spectrum. A board with 27 responsive light-up keys would be prohibitively costly.
That said, the puzzle board itself was cheap. A wipe-off board with a crayon, and not even a couple of plastic legs to prop it up. Put that next to the standard Wheel of Fortune home game at the time, and it was easy to see which one would be more "worth" your $12.99 or whatever. Also, I don't think there was any play money included at all. I remember making my own for it.
Even with the cheap-outs in production, though? Still a fun game to play, which is more than can be said about a good number of others in this topic.
Also, strangely, while COAL only got one "edition" of a home game, that appears to have been made with three different "versions" of the keyboard. There's the one pictured on the back of the box, with opaque plastic and the raised sliding letter "buttons." There's one where the plastic buttons get replaced with printed cardboard rectangles you punch out from a sheet. And there's a third that uses a flimsier, clear plastic to lay the cardboard letters on, which is the version I got as a kid. Search for the game on eBay and you'll see the differences in the listings pretty quickly.