Good question, but frankly the vendors often shift merchandise with seasons. Not much help, but there are also many other changes taking place on island. Basically, what was - might not be anymore, but what wasn't just might be. You might have better luck at the big Saturday swap meet in Kahului.
There are craft fairs held regularly at Kaanapali Beach hotel, all vetted, but even if no ukes, wood is wood and talking story reveals a lot. Crafts same at Kaanapali Shores, not as often. Craft fair under Banyan tree, still my brain does not recall ukes. Again, things change. Many changes on Front St this year and beyond.
Under the assumption that you are searching for less costly instruments, many of the gift shops have them.