You can always offer 20-50% under asking.
Typically, formal offers are sent by the buyer's broker to the seller's broker in writing via email. In some cases, a buyer will also write a personal note to the seller to send along with it. That letter is known as a house offer letter.
The basic elements required for the agreement to be a legally enforceable contract are: mutual assent, expressed by a valid offer and acceptance; adequate consideration; capacity; and legality.
There are four essential elements of forming a contract: offer, acceptance, consideration, and intention to create legal relations. Beyond this, the terms of the contract must also be unambiguous, and the parties must have the mental capacity to agree.
Valid Offer: The offer must be clear and specific. Acceptance: The offeree must accept the offer without modifications. Adequate Consideration: There must be a fair exchange of value between the parties. Legality: The contract's purpose must be lawful.
The Requirements of an Offer The statement of offer must show intent—The statement must reasonably be interpreted to indicate an intention to enter into a binding agreement. The offer must be communicated to the other party—An agreement cannot exist unless the offer is communicated.
The seller can back out for reasons written into the contract, including (but not limited to) contingencies. The buyer is in breach of the contract. If the buyer is “failing to perform” — a legal term meaning that they're not holding up their side of the contract — the seller can likely get out of the contract.