Are they damaged? If not, they are likely not the cause of any issues you are having. They rarely go bad.. In any case, Pinball Life lists at $12.95 and Pinball Resource is $15. You'll have to factor in shipping, but they are usually similar.. You'll also save the cost of a stamp and a check with Pinball Life.
https://www.pinballlife.com/williams-fl-21-37528-400-flipper-coil.html