There is more to a home purchase offer than the price. Ideally, the offer, including any counteroffers, should encompass all the terms and conditions that will apply to the purchase transaction.
In some states, attorneys draft purchase offers. In other states, like California, most residential purchase offers are filled out by real estate agents using pre-printed contracts that were drafted by attorneys. In either case, make sure to read the offer and understand it before it's presented to the sellers.