zoolatry.com 18 dollars a walk

My family will be moving soon to the Chevy Chase neighborhood of DC with our golden retriever. Please recommend a dog walker who services this area and is capable of handling large dogs.
We've never used a dog walker before, but my work schedule will be changing and we may need someone a few times a week when I'll be away from home for longer stretches of time.
Also how much should I expect to pay?
Thanks!