Look no further than your local realtor, you get years of experience knowledge of market trends, assistance in budgeting and much more, but best of all its free for the purchaser.
When an owner decides to sell they enter into a contractual agreement with a Real Estate Brokerage and in this agreement there is a specified commission paid to the brokerage on satisfactory completion of said deal. The listing brokerage then pays the purchasing brokerage out of that commission.
Now after you have found an agent you feel has the knowledge and skill in the area you are looking you then have two options.
The first - you become a client of that agent. The brokerage under legislation has a greater obligation to look out for the interest of the client. Follow your instructions, protect you confidential information and promote and protect your best interest. This will require you to sign a contract with the brokerage for a set time period and you will use the brokerage for any purchase in the aforementioned time. You are no longer able to switch agents until expiry of the contract and there may well be a carry over clause.
The second choice is a customer service agreement . A realtor will still assist you in the purchase of a home but will not have the same level of responsibility as they would a client. They will still show homes and present offers, but not necessarily give advice and are not required to promote and protect your best interests. But under a customer service agreement you can work with more than one brokerage.
Whether you are a customer or a client the brokerage will still have to act fairly, honestly and with integrity and provide you will conscientious and competent service. Keep in mind some brokerages may insist on a client contract, if this is the case read it carefully, ask questions or consider legal advice.