Estate sale Fuselier speakers for $370 but I know nothing about them.

weebeesdad, unfortunately there is no way to test them. They do look to be in spectacular condition, but that's not to say whether they have been used to death or not. 

For an hypothetical, let's just say the driver is shot.  Where does that leave me? Again, I'm very new at this but I assume the craftsmanship of the enclosure is probably the most important part of this, right? Could drivers and other parts be replaced yet still reproduce the quality tones that John was inspired to create?

Sorry for the ignorance here. I'm just getting into the hobby but I did not expect to be diving in this soon like this.  

"I assume the craftsmanship of the enclosure is probably the most important part of this, right?"

Not really, the drivers, the crossover and the enclosure are all equally important as they work as a unit. The drivers can be replaced or serviced as can the crossovers if needed. Don't worry about that, just buy the da*n speakers and be done with it. Then we can move on to what you will power them with. You have to start somewhere, we all did.

Alright dill, you drive a hard bargain. I'll be picking them up tomorrow. 

Excellent!

Taking an expensive receiver with you. Hook them up with a CD player and see how they sound.