I come on here to give the people who don't know some insight from an insiders perspective, not to be undermined by others. Please allow me to clarify the original comments below.
A buyer in the NYC market is open to work with more than one realtor/broker as that is a consumer's right. Anyone advising you that they will not work with you unless there is a contract is simply aiming to get you to work with them exclusively, often in order to eliminate sharing of the 6% commission standard here in the NYC area. I am a Real Estate Board of New York memebr and that violates REBNY policy. There are usually only contracts endorsed between a seller entering an EXCLUSIVE agreement with a seller's broker in the NEW YORK CITY area. While I respect my colleagues here, this is the honest truth about the market which I work in.
Some people can insist that they won't work with you unless you sign an agreement, but I am a big believer on trust. If you can't trust me to honestly represent you as your buying agent and we need to sign an agreement that I will do what my job duties are, then why would you want to work with me? If I have to make every purchaser sign an agreement that they will work only with me, why would I want to work with them? That just sounds a bit fishy in my book. Too much politics involved there and the last time I checked, I am not Obama and Laurie is not Hillary.
In the markets outside of Manhattan and the five boroughs, this may be the case. I don't sell homes in Long Island at 4% from the seller and thus try to eliminate a co-brokerage situation, so you'll have to figure that one out on your own if that's where you are looking.
Think about it, if you are going into a closing and the seller has a broker and a lawyer, wouldn't you want the same representation so as to ensure the maximum bargaining power? Also, purchasing a home, be it for primary residence, pied a tierre or investment is indeed a VERY emotional process and not all just logic, numbers on paper and reason. This is ESPECIALLY true if we are talking about Manhattan. Why else would a person spend a million dollars on a 600 sf new development condominium studio or one bedroom when they can go to Long Island and get a proper house of 3000 sf?
A person using a real estate agent (broker and realtor are often interchanged by clients based on where you are from) for a purchase needn't worry about who the broker represents if that broker knows what their job is for that buyer. That is, if he/she is not merely the listing broker representing the seller. We work with renters, buyers and sellers in most Manhattan firms, often all at the same time.
Here in NYC, I have met clients at open houses, if they were not interested in that seller's property, I do not push them on that property. While my goal for that seller is to sell that property, there are plenty of buyers to go around for that property and if a buyer comes to me looking for advice or for other options, am I supposed to turn them away? That is poor customer service. I listen to the needs and use the resources I have by being in the brokerage community to find other more suitable options for the needs.
I am not going into Riverdale Long Island and telling buyers "you must sign something as it makes sense to sign something", as that is not my area of expertise. Also, at the end of the day, most sales clients do not want to be told to sign anything in the Manhattan market. They usually want to feel a few brokers out, as that is just a savvy consumer's nature. If the shoe doesn't fit, you try on a new pair. You don't leave the store with the wrong size on because the salesperson told you to sign an agreement that you will only buy shoes from that store and the shoe that they say to wear!
I am here to offer my advice as I do know Manhattan, Queens and Brooklyn quite well and can offer all sorts of advice on those areas. A true buyer's agent here earns the trust of the buyer through the proof in what they are showing. If it seems like they are showing things you specifically asked not to see, why would you want to be locked into a contract with someone who is self serving and not at all listening to your needs? We are 100% commission based here in Manhattan, so the number one goal is to ensure that the client is happy. If I don't do that, I don't get paid. It's really that simple. We can sign a "you represent me to make a purchase" agreement or not. Most agents don't see it that way and only think about how to ensure that they are not loosing a client or how to get the whole pie. I prefer the 10% of something, beats 100% of nothing approach. To each, his or her own.