But you said that you don't have S-vid hookups.
It's gonna be expensive no matter how you attack it. You're not going to achieve a high quality image with cheap Y-cables and such. You've just got to decide how valuable it is to have these consoles properly connected. If it's really important, then just save them pennies. If not, composite and move on...
That's why I wanted a S-Video to Component or HDMI converter.
I just want a little better picture, Composite is mostly ok, but the Reds are handled terribly. To get a slightly clearer picture for $30 for a converter + $10~ per cable is fine for my curreny budget, Vs $70-$100 per system for a mod.
S-Video VS Component on Gamecube are that far off, according to the comparisons in this - https://www.youtube.com/watch?v=hVX81e6Ig-s
The good thing about S-Video is since it's Luma (Picture Brightness Intensity) and Chroma (Colour Infromation) it should for the most part get rid of that red issue you're speaking of since it's separates them into four wires (Luma, Chroma, Ground, Ground). The convertor that converts S-Video to HDMI does a decent job at it.
When it comes to HDMI, the better the analogue signal you're converting, the better the digital signal will look. Composite to HDMI is horrible, but S-Video to HDMI is tolerable.

I do recommend getting decent quality S-Video cables. A cheap cable could have more interference, where a well shielded first party s-video cable, Hori s-video cable, or Monster Cable will result in a better S-Video picture when converted to HDMI. I just gave my friend all Monster Nintendo multi out cables and she was ecstatic on how much it was a step up from composite. Hori does make other system cables, but they're more well known for Nintendo third party cables. However if you're on a budget I completely understand getting a bit cheaper cables.
Ask for S-Video vs Component, the higher you go on the analogue spectrum, the better the picture becomes, RF to Composite, huge difference, Composite to S-Video another huge difference, S-Video to Component, a little bit better, then component to RGB unless your an videophile most people won't notice the difference but there is a slight difference in colour space.

The biggest reason S-Video or Composite to Component video is so expensive is because it's having to break apart the picture information from an already lesser signal. The French NES with no modifications converted composite to RGB. Compared to real RGB, the colours were washed out, the picture wasn't too sharp and it was fake RGB, however since it was on CRT's most people usually didn't care. HDTV's make everything "too perfect", if the analogue signal is not high quality then it will show up.
