I've found that almost every on line travel agency is within a couple of dollars of each other. In fact, many times I've found the airline websites are about the same or even less expensive than the agencies. I find it best to go to my local agency in town. They've been in business for 35 years and I just tell them exactly what I want and they get it for me at no additional charge and the lowest possible price. You can never be sure with on line agencies exactly what you're getting and for how much. Some agencies you can't even book your seats or know what all is available.