1989 Force 150 ignition coil question.

I need to replace two of the ignition coils on my motor. I looked on a website called iboats and it shows that for the year of the motor I can get a CDI coil for $100 dollars or a Sierra coil for $31.29. The Sierra coil says it's for all the 150hp Force motors from '89-'94 but it's a completely different shape. If I can save the money, that would definitely be preferred. Anybody know anything about this?