Lisa: The Realtor to contact is a Realtor you would like to assist you in finding the right property for you. You can always just go from listing agent to listing agent. Doing so leaves you without an ally to help you find all houses that are available and even those that just become available. The agent you choose (and it's your choice in that case, rather than luck of the draw of the seller's choice rather than your own) can also get to know your wants and needs. While, as a seller's agent, I don't mind selling a property to a buyer directly or by becoming a dual agent, I usually find that, unless the house is exactly "the one," that the buyer goes on, bumbling around, hoping to find the "right one" by driving around and looking for open house signs or by looking on the web. While this may be a fun way to spend a Sunday afternoon, it misses many houses that might be a much better fit and therefore much more value for their cost.
Think about it!