Let's call this what it is... your biggest shopping purchase. I would want a professional with me every step of the way in making sure I spend my money wisely. Having a Realtor can help you do just that in the most financially secure way.
What does a Realtor have that I need?
A Realtor has access to the most updated information in all aspects of the home buying process. They also have the ability to narrow your search to the homes that best suit your needs instead of wasting a lot of time online or driving around. A Realtor can also advise you on which homes are priced well for the market and what features to look for while shopping for a home. A Realtor also has access to lenders that are reputable and can help you shop and compare what will be the best mortgage for you.
Using a Realtor to negotiate for you can literally save you thousands. Having someone who represents you in the biggest transaction in regards to price, closing costs, closing date, repairs, etc. just makes financial sense.
For a variety of reasons you should use a Realtor to help you save time and money. Having someone on your side that is on top of the entire process only helps you sleep better at night.