Final answer:
Eber & Fowler's chances of successfully suing The Bander Company for an additional $400 are low unless the contract included terms allowing for fee adjustments. Without such terms, the agreed amount of $3000 is enforceable.
Step-by-step explanation:
When Eber & Fowler (E&F) agreed to provide services for The Bander Company at a reduced rate of $3000 after negotiation, they entered into a binding contract at that price. If E&F sues Bander for the additional $400, their likelihood of success largely depends on the terms of the contract. In the absence of a provision that allows E&F to unilaterally increase fees due to unforeseen circumstances, which is not mentioned in the provided scenario, E&F's chances of winning the lawsuit seem slim. The previously agreed upon amount of $3000 would be enforceable, and any attempts to charge more without Bander's consent would be seen as a breach of the contract by E&F.