As a general rule, just because the price accepted by a party to a contract (such as for leasing, purchase price, etc.) is less then others are paid, less than the market normally pays, or is less than the property or service they provide is worth does not mean the contract can be broken jsut for that reason.
Unfortunately, when a contract is signed the reasons why the contract can be broken or stopped are found in the contract itself. If a contract is valid when entered into, meaning there was an offer made, an acceptance of that offer was made, the parties had capacity to enter into the contract (such as they were not minors or had mental deficiencies at the time of contracting, etc.) and there was consideration (something of value was exchanged), and the contract was for a legal purpose, then the parties who wish to end or break the contract must normally read the contract to see what, if any, termination or ending options the contract allows, if the contract allows for renegotiation, amendments, modifications, or other ways to alter the contract and, if it does, if those changes must be accepted or if they can just be suggestions which the other party does not have to accept. A failure of a party to honor a contract, even if they feel it is unfair or that the other party breached, may allow the other party to take them to court to sue for a breach. For this reason, it is always best to have an attorney fully review a contract before signing it and/or before acting or failing to act on it.
There are some situations where a contract may also be terminated, even if the contract itself does not allow for it. For example, if the other party to the contract either lied or misrepresented any facts of the contract or used any kind of deception or other misrepresentation to a person so that they would agree to enter a contract then that person may later file suit to be relieved from the contract; if the other party commits a breach of the contract; etc. There are also some circumstances where a court may find a contract so unfair or against public policy that it may declare it void or where a party did not allow the other party to a contract to have an opportunity to properly review the contract.
You should speak to an attorney in your state to have him or her fully review the contract and how the negotiations occured to see if there are any reasons you may be able to terminate this contract or re-negotiate its terms.