Personally, I would opt for tortoiseshell from
Greven. Maybe a brownish-red/orange tone like this (they offer many other types):
The thing with Greven is, the tortoiseshell is the closest you will find to genuine tortoiseshell anywhere. All of the other tortoiseshell I have ever seen has been piss poor when compared to this stuff. The pickguard in the image above was moulded rather than cut, so it isn't perfect which sort of gives it an even more authentic vibe.
If John Greven still offers this service (maybe he can sell a sheet if you prefer it to be less rough?), he used to charge around $50.