I got the coveted Monster GameLink component cables (with the optical cable and mini dongle) off of eBay for about $20 shipped. They were in a slightly beat-up/taped-up package, but otherwise looked brand new. I trash Monster Cables with the best of them, but there really, truly is a difference with this product. It looks way better than the component cables that came with my 360.
Search around and see if anyone is offering them cheap. While I was searching for these a few weeks back, I even saw some go for as low as $6, so give it a shot.