I suspect that those who don't see a noticeable improvement w/ DVI over component on a digital medium (DLP, LED, plasma, et al), probably have poor DVI cables, whatever the brand. That said, I bought a Monster DVI cable when I purchased my Sammy DLP and companion Sammy DVI DVD player. When I got the 811, I switched the DVI to it and I use E* component cables for the DVD player (can't yet stomach the cost of a DVI switch). The E* component cables do an adequate job. My DVDs look like everybody else's progressive scan PQ, which is to say, no where near what my DVDs looked like through DVI.
As to Toslink, I use Walmart's stuff, mostly Phillips at about $15. I'll spend more on wire because the quality of the material carrying the signal can affect the signal. But, Toslink technology doesn't depend on the material, so why pay more. It's sort of like a DTV signal. You either get it or you don't. If you don't or have noticeable problems, return it for another one of the same brand at the same price.