The dealer gets paid on the higher rate. If you do not like the rate just move on. If you do not like the price, again just move on. Just like if you are looking for appliances. As for the best price if it isnt what you would like to pay go somewhere else. But they disclosed what the best price THEY could do on the red tag and told them that. Now if the interest rate was also to high go to the bank yourself or maybe try a credit union.
Now if there is more to the story I may understand but from what the OP posted it is that they didnt like the price or the interest rate so they are bad people and dont buy from them. Not a legitimate excuse.