My understanding is that audiologists who will work on a fee-for-service basis are rare, but they do exist. Finding one will take some digging, and as far as I know getting insurance to pay for it could be harder.
If you’re technically-oriented at all you might consider the DIY route. Right click on the avatar of forum user “pvc”, or select "Hearing Aid Self-Fitting and Adjusting [DIY] to get to the DIY world. You will need the Target software used to program Phonak hearing aids, and a Noalink Wireless Bluetooth programmer. ($125 - $175 on eBay, Amazon, etc.)
Then you hang out on the DIY forum to learn how these things work from the inside. It will take awhile. I have all that and am a retired engineer, but the farthest I’ve gotten is to read the original setup in my hearing aids so I can compare it to adjustments the Costco HIS made for me just recently. I didn’t really understand what he was doing or why during that last session, but I hope to gain a better grasp in time. I’m banking on the DIY forum to be my teacher.
Also worth knowing is that when I got my first assessment (after which I was knocked over at the costs I was looking at), that first visit pre-sale was paid out-of-pocket. Perhaps that’s common in the industry? It’s been suggested we should get a new test annually, so you could go to a new audiologist as a “first-time” patient, get tested, get your audiogram (which they are required to give you) and then program any changes into your aids.
Or if you can find a new audiologist at a clinic instead of a private practice, you can get fee-for-service care.