In addition to custom lutherie, I refret instruments with either non-nickel stainless steel or hypoallergenic gold-colored EVO fret wire. I do not install regular frets because they contain significant amounts of nickel, which I am very allergic to. Because both fret materials I offer are significantly harder than regular fret material, I have to factor accelerated tool wear into the cost.
Stainless steel is much harder than regular frets, so they last much longer. Some say they make an instrument sound brighter or have more sustain, but I have yet to demonstrate that. The alloy I use polishes to a nice silver color, but is slightly more gray than nickel frets.
The EVO fret wire is gold-colored, hypoallergenic, and less hard than stainless steel (but harder that regular frets). Personally, I recommend the stainless frets for the sake of durability, but the EVO wire works great, and is one of very few options if you want cool colors.