Something like $10k for the actual device, the surgery is about $50k, and then the costs involved with the audiologists, follow-ups etc. However, the device should be replaced every 5 - 7 years, or it's detrimental to your hearing.

Moisture is a big destroyer. It never occurred to me at the time, but now I am beholden to Med-el for life, it's literally a lifetime subscription :)