Legal Question in Business Law in Illinois

Probably not. Trade secrets are protected by the Illinois Trade Secrets Act and do not require the presence of an agreement. It is unlikely, however, that a supplier's pricing is a trade secret, although a specially negotiated price list for a single customer could conceivably be a trade secret.

It is also possible that a supplier could come up with another novel argument. For example, if the information were disclosed solely to injure the supplier (rather than to negotiate a better price from other suppliers), the injured supplier might be able to build a case of some sort of intentional tort.

But, generally, the concept is that "information wants to be free." Unless there is a specific agreement restricting a party from divulging pricing information, it is difficult to see how the disclosure would create liability for the disclosing party.