Brokers make their money on commissions and tend to use captives as a defensive mechanism. Additionally, unless the captive manager operates at arm's-length from the broker, you may not get unbiased advice about how your captive can be best utilized. An independent manager doesn't have to keep a parent broker or insurer happy. If you want what amounts to a bookkeeping service, the price should be low. Fuller services will cost more.
Captive management is a competitive business and fees are usually in line with reality.
But not always. Your manager, like any other company, should be aiming to become more efficient. Some captive managers offer new clients a rock-bottom price that seems to good to be true. And it is. Also, watch out for broker-controlled managers that offer captive services at severely reduced fees.