As I understand it, yes, the Mad Catz pack is cheaper than the Microsoft packs. I personally use the cables from Monster Cable, as I used to work at an a/v place and got my discount. I noticed a big difference when upgrading to S-Video from composite, however, I doubt that the Monster cables are much superior to the ones offered by Mad Catz. I have not seen the performance of these cables personally, however, I like the Mad Catz products the best out of the third party hardware publishers.
Also, you probably know this already- if you have an HD capable set, you should pick up the component cables and skip the S-Video.