Zip Realty will do full-service for around 4% by giving up a big chunk of their end. They can afford to discount by virtue of not having offices to pay for - their agents work from home or in their cars with a laptop.

Most other agencies will price-match. If you say "I was thinking of using Zip because their commission is X..." you'll find you can get that price or better from the agent you're talking to.

I sold my house in Mountain View through Zip three years ago and was generally satisfied with the experience.