A few years ago I replaced my original, ugly, and beat up (in my opinion) aluminum rail (
http://www.wellcraftv20.com/gallery/album06/Dock_2010) with a black rubber one that accepts a 5/8" rope (
http://www.wellcraftv20.com/gallery/.../Spring_2012_b).
It took me only a few hours with a drill/driver to remove the old one and install the new one, and I didn't need any help. It cost me about $300 total for both the rubrail and the rope. The new rail came with a round black plastic insert, but I used a separately-purchased nylon rope instead. I thought the total cost was a very reasonable price for what I consider to be a great aesthetic improvement.
Before I bought that rail I searched this forum and followed one or more recommendations I found. I can't find my receipt at the moment, but if I do I'll post the name of the manufacturer and model number. I know that it's a very standard rail that's widely available from marine supply sources. I don't think there are many different rail manufacturers.