@dkeefe. My gut feel is that the brands are all probably similar in cost, the models within each brand vary depending on their sophistication. I had Phonaks that I loved but then my hearing lost clarity so I now have oticon Opn1. The phonaks had great directionality though. I had my hearing tested in NYC by a somewhat renowned audiologist. Her choice for me was Widex, but the audiologist who would be servicing them at home did not work with that brand, so the Phonaks were her second choice for me.
I don’t know about Costco but hearing aids do need servicing and if that is not included it may end up costing as much as purchasing from an audiologist.
My hearing loss started about 14 years ago, age related, but my daughter has a hearing loss that she was apparently born with. Her current hearing aids are ReSound, and for her they are the best she has ever had.
This is such an expensive purchase, I hope you are able to find some that are very helpful. Most audiologists will give you a trial before you have to commit. I actually had a different aid before settling on the Oticons. What is best for you varies depending on your loss so having an excellent audiologist is important.