We just bought a house (in-contract, waiting for the closing day).. and in our experience... real estate agents were nothing but a reason to pay more for a house. We were being shown houses not worth their price tag because of the 6% commission and because the good ones were already gone with the "multiple listings". Take this experience for example...
We saw an ad for sell-by-owner for $319k. 5 weeks later, the ad is still there... we call him up... he tells us he just went and listed with an agency. His price is now $369k. Are you f$@king kidding me? We saw the house based on his promise to sell to us for only $319k anyway... if we wanted it. We show up, and the place is worth < $300k in our eyes.
Sellers jack up the price so ridiculously to "make up" for paying that 6% commission. In the seller's eyes, it's comparable to having to make up for a deductible on insurance when you claim more than you actually lost. My advice is to look for sell-by-owners and visit a lot of them.
We bought ours for $330k from sell-by-owners while the same house down the block in MUCH WORSE condition/setting (we saw it thru Century21) was going for only $7k less. Needless to say, that one is still on the market.