Cost of BAHA implant surgery varies due to a lot of different factors - doctor's fee, hospital fee, whether you use an anesthesiologist or not (if you have local, you don't need an anesthesiologist). My insurance company was billed somewhere in the neighborhood of $50,000 from what I recall (my surgery was 3 years ago; done as an outpatient with local, and lasted all of 90 minutes from start to finish), but they discounted it DEEPLY and neither my doc nor the hospital got anywhere close to what the original bill was.
The cost of the processor is typically set by your doctor and it varies. Sometimes the processor is included in the hospital bill, sometimes it isn't.
I'm not a lawyer, but what your insurance company did to you doesn't sound legal. I'd take Jim's suggestion and contact your state insurance company.
Most doctors will not even agree to schedule a BAHA implant surgery until they have proof of coverage from a patient's insurance company - since there are still a lot of insurance companies out there that don't cover BAHAs.
In the end if you do have to foot the bill yourself, see if you can work out a payment plan with the hospital and ask the doctor to give you his professional discount. Docs mark up their services, as well as the cost of the processor. If your doc did the surgery without proof of insurance, IMO, he should "eat" some of his profit.
Jan