A bit OT: @Burton: Do you also know the equivalent types for a replacement of the front brake lever?
Are you looking for the equivalent of a stock lever because the replacement $16 part is too much or are you looking for more options in general?
If the latter there is hope but it will cost slightly more. If it were me I would find out the bar size of the bike then find a bike which has good aftermarket support and the same bar size then buy a used brake reservoir to replace the stock one. That way you can have the options you want. You need to learn to bleed brakes first unless your willing to pay someone to install it.
If the former and you just want color options then buy a stock one and have someone sand blast it then anodize it, assuming it is aluminum if it is steel then powder coating is in order. Minor machining will need to be done on the inside of the brake lever where the fulcrum is.
Or if the former and you just don't want to pay $16 then I can't help you
EDIT:
Just had a thought, since i don't own a zero yet, if there is a sensor specific to the zero on the brake reservoir then there is one of two tracts you can take depending on the level of integration if replacing a reservoir
If it is just a different switch swap the default one for the new one on which ever new reservoir you install. If the threads to install it are different then you need to fabricate something or modify the new reservoir. Obviously this would require some skill and testing, lots of testing.
If however zero programmed for a 'stock' switch then your probably fine but something tells me it might be a zero specific switch.