If there was a contract between you and the supplier that was in effect (e.g. had not expired; was not due for renegotiation/renewal) and that contract specified prices and quantities, you could enforce that contract against the supplier. However, if there was no then-in-effect contract, the supplier could raise prices and minimum order quanties to any level it wanted, regardless of its effect on you: business 1 is not required to take into account the impact on business 2 in its operations or decision making.