As a buyer, do I need a realtor?

[Dakota Shaw]

I'm constantly reading about REI now and I'm still not at a knowledge level where I feel comfortable to jump in. I do, however have the savings and finances to start buying properties, especially because I tend to be frugal and budget aggressively with my personal finances. And this budgeting and frugality leads me to my question, which may seem naive so please bear with me:

As a buyer, what value an agent provide for me, and if you are an investor who is purchasing and using an agent, why do you use one?

Buying using an agent- even among investors- still seems to be the norm. Why do investors use an agent, and would it be recommended that I start my search with a real estate agent, especially considering:

• I keep up with local listings and have found several properties that over the last few months on my own that could make financial sense.
  
• As a negotiating strategy, I could match an existing offer on a property, but offer to do the deal without a buyer's agent/fee (saving the seller 3%). There are other negotiating strategies I could envision as well.
  
• I have started collecting data on what houses sell and for how much in my area, along with stats, to make sure I understand what properties are worth and how long they will take to sell, so I'm not sure there is a lot of value-add an agent can provide there either.