Rental rates on the same size machine can vary up to 50% by rental house. There is value to a consistent good supplier. Loyalty is important. But at what cost?
Many dealerships are very competitive with each other. I have seen prices reduced by 50% just to keep the competitor out of an account. Dealerships are trying to protect future rentals from your account.
I know some accounts that get up to 8 quotes on their possible rental equipment needed for the season. Some get very good pricing. This may be an area you should consider some new ideas.