No idea if this is any good to you now, but when I needed a PS2 component cable I bought an Xploder upscaler disc thing that apparently added progressive scan to every game. What it actually did was squash the image into a tiny rectangle in the middle of the screen so it's a complete piece of crap, but it cost less than Ł5 delivered and came with a component cable making it easily the most economical way of getting one. Got my hands on a new one about a year ago so I'd say it's worth 5 minutes or so of Googling/eBaying to check.
Quoted in hope...!
Does anyone know where you can get a PS2 compatible RGB lead please?