To add to all the time/fees mentioned below, in Orange County both OCAR and PACWEST which are the local boards cost about $750/year to join. This is what you need to have access to the MLS and get a Supra Key which allows you to access any lockbox. Keep in mind that in todays market which is rattled with short sales and bank owned property it is usually not about writing just one offer. I would caution you that while the perception is that we make a lot of money for writing offers, it is much more time consuming that you may otherwise think.
Sure you can represent yourself if you get a license. But it is a lot more expensive then you may realize. Typically 60 - 80 hours of schooling followed by a state exam ($100 or so), licensing fee (another $100 or so), some states require that you be bonded (cost unknown), obtain and pay for an errors & omissions insurance policy ($300 per year plus per transaction costs), pay the dues to become a member of the local and national association of Realtors, purchase and pay membership fees for the sentrilock or other keycard system used to access homes in your area, attend classes on contract preparation, join, pay for membership, learn how to use and understand the MLS system, negotiate what percentage of your commission will go to your broker on this transaction (typically starting at 50%), pay a percentage of your 1st commission to your mentor....and so on and so on.
This really isn't a dabbling kind of business. And after all that trouble you could really shoot yourself in the foot by overpaying for a home because you aren't an expert in the area. Let's say your were buying a $200,000 house and the co-op commission to the buyer's agent was 3% or $6,000. Give your broker half of that and you are down to $3,000, pay your mentor 25% and you are down to $2,250, deduct your start up costs of about $1,500, and then pay yourself $10 per hour for every our you attended class and so on. Now how much have your "earned"?
I could take classes at H & R Block to do my taxes and really save some money...but I'd prefer to pay an expert who specializes in accounting and current tax rules and regulations. A great buyer's agent who really knows your market and can guide you through from A-Z is FREE to you. Spend your time and money on something that really interests you and have some fun with it!