Yes, our broker and the AOPA broker.
If two brokers haven't been able to do better, there may not be a way to get what you want at any lower price. I know that once past 75, the insurers get increasingly reluctant to cover people. Have you considered that it might be your 86-y/o partner whose age is driving the price? Could be a hard and harsh decision to make, but perhaps you should consider asking what would happen to the quote if he wasn't flying the plane any more. Alternatively, ask about limiting his flying to only with a qualified younger pilot (maybe even you) in the second seat.