My scanner will scan some negatives fairly well without a light. It has a setup for 35mm, but it's only for 35mm, and it's never worked. To the point of making the scanner not run when it's plugged in.
Instead I put my wifes lightbox from the sewing store upside down on top of whatever negatives I'm scanning. They're not cheap at around 35 dollars or more, but cheaper than a new scanner.
The stuff archival supply places sell for negatives is about as good as you'll find. Library of congress has a few pages of instructions for archival storage of nearly anything. They're a bit over the top in some cases, but it's what's currently know to work best. Even partially following the guidelines is better than nothing, although I've bought stuff that was stored horribly that was just fine. (And stuff with nearly archival storage that had problems
)
Steve B