I am a new user. Have had the KS10’s, $!,399, for about 6 to 8 weeks. I would start there as they are the lowest price. They have a 6 months trial period. You enough time to make a reasonable decision. An important factor is how far away the Costco is. You will have to go back for return visits, and if the Costco is a long drive that could be to be a pain.
My local Costco has been very busy with appointments, including return appointments, about a month out. I did do one drop in to get the ear pieces changed, and that was fine. It has taken me about a three months and 4 trips with another trip scheduled to get mine to what I would say is acceptable.
Good luck.