I had a Kona Kaboom(2000 - an aluminum w/ steel fork SS). What a great bike, it was incredible for the price. A complete SS ready to go with nice quality parts for cheap. The Kona Unit looks to be even nicer with the steel frame.
I think it would be hard to beat the Kona Unit for a complete ready to go SS with good value, the Bianchi is probably also comparable but I tend to really like Kona for mountain and cyclocross bikes(I have a Jake Cyclocross). But, the Bianchi also looks nice.
That said, if you want build one up it would be hard to beat the Surly. They are a great and really tough frame/fork for the price. I really like Surly products as well(I have a Crosscheck that was a SS for a while, now has gears), and that is great bike and durability is it's strong point for sure.
The Redline would be the one if you are on a stricter budget. Just has some cheaper parts and the frame may not be as refined as the others, but would get you into it for a good price. I don't have any experience with Redline, but the price sure seems right.