Another vote for kingwood here. It's close in density to ebony and, at least in my experience, has a very similar feel to it.
Someone mentioned a finished fretboard. Having owned a Rickenbacker... no.
It feels fine, but nothing like ebony.
All that said, I REALLY wish Warmoth would add Richlite options. It is my favorite fingerboard material by far. It feels VERY similar to ebony but has none of the CITES/IUCN drawbacks. There are so many color options available too. I had a Hagstrom with a Richlite board and nothing's felt quite as good since.