I use King alot good pricing, fast shipping and good customer service. There is also another place called Architectural Iron, believe they are around New Jersey. They have a bunch of stuff also and balusters can be from a few dollars to several hundred each. Another place I have dealt with is Lawler down in Alabama, but to order from them you have to be an approved business(fill out paperwork etc) to get pricing/catalogs. King will have pretty much anything you need though. I've been out looking at gates other guys have built and the client wants a smaller walk gate that is similar. One look thru the King catalog and find out other than the tube around the gate everything else was from King. Makes it easy to duplicate that's for sure. Here you go,
http://www.kingmetals.com/http://www.archirondesign.com/search.aspHave not dealt with Architectural Iron as of yet but have used some of their products during the design/bid stages but then clients get a shock. They start out with grand ideas, so you design a grand idea and then the price usually makes them say, "not right now". Get the whole beautiful design, love the gate, would like it but just gonna go with wood right now. Anyhow, more than you needed. Hope the links help out.
Shawn