Wanna add, why are slides considered more expensive?
Say we compare Velvia 100F, Velvia 50, Kodak E100VS, these are the more expensive slides, against say, Fuji Reala 100. I think the price is similar? (sorry if the pricing is out, as I bulk roll my own slides)
E6 processing for slides varies. I get mine done at Ruby, I think it's 4.20? RGB is 5 dollar plus, but it's done in 3-4 hours. Colour lab @ adelphi, i was told is around 6?
For negatives, if you wanna develop C41 and print all, may cost more VS slide film + E6 processing. Unless you develop negs, then scan to CD... may be cheaper, maybe not.
Still, negs can't be beat in certain situations where slides die. E.g. mixed lighting, or difficult exposures. This is where I feel digital rocks: white balance. No need for CC filters.
For slides, I only choose keepers to mount; seldom print. Rest goes into my big file of "didn't make the cut".
Alvin