$25 per spark plug indeed seems a little on the high side. But it might not be extremely high.
There’s two different types, copper & iridium. If you car’s maintenance schedule says to replace the spark plugs ever 75k+ miles, those are probably iridium type. Those are more expensive, $12-$15 at parts stores, but $25 each wouldn’t be out of line if purchased as an oem plug from a dealership.
Copper plugs (both of my vehicles use this type), the replacement interval is usually recommended at about 30K miles. Those plugs are usually priced $2-$4 each .
In any event , $233 to diagnose the problem & replace the spark plugs, and it solved the misfire symptoms, that seems like a pretty good deal to me. I actully don’t see how they could do it for $124 in labor. Seems like it would cost more than that. It takes me around 45 minutes to change my Corolla’s 4 spark plugs, and no diagnosis time. Labor rates in most areas are $100 per hour or more.