They used to be really reasonable. The original 10w6s cost $70-80 to get reconed by JL back when they would do them. Sadly they don't do recones on those anymore.
My take on the price is that the purpose is to discourage people from abusing the drivers. If you knew that being a dumb@ss was going to set you back $400 per instance, you might actually think twice. I've got functional subs that are older than members of this forum. If you don't abuse stuff it actually lasts and you don't come in asking about recones.