Everyone involved in the deal gets paid through the deal. Whether it charged to customer directly or collected through the dealer.
If a dealer is offering 300 odd per car to broker it’s because the car selling price is raised by that amount.
If you really go deep and get that bottom dollar from the dealer he won’t pay you that referral.
Again as explained earlier you can’t survive if your numbers are higher than other brokers, let alone dealers.
I get request many times by customers asking to beat a quote from another broker. Sometimes I can push my dealer to do it and other times like in post COVID era they don’t want to fight for the sale and let it go as inventory is limited.
There is nothing wrong in shopping between dealers/brokers, in fact I suggest my customers to call few dealerships and ask them to beat my quotes just so they realize that after paying broker fees it’s still better than getting the deal directly at the dealership.