I have seen them at Costco and the Phillips HearLink model sells for $3400 CDN including the charger. I believe Costco used to carry Bernafon and stopped when they brought in the Phillips model a few months ago. About all you can do is try and find the technical specifications for each and compare them. Costco is pretty good about supplying specs for the Kirkland Signature model, but not so much with the ones with the brand name still on them, but made for Costco. If you do a search here, you will find some reviews on them, which generally have been good.
Here you can get a walk around the store, but that is about it for a trial. But, their return policy is excellent. Perhaps get a Costco credit card, buy them on credit, and just return them if you don’t like them before the credit account needs to be paid? A free trial Costco style…
If you have dismissed the KS9 you may also want to consider the Rexton Adore Li. It is much like the KS8, but rechargeable.
Edit: You may want to to check this thread on the HearLink if you have not already. Lots of discussion on how the HearLink compares to the Bernafon and Oticon S.