i've replaced mine and didn't have to replace masters at all; all i did was bleed the brakes
rizoma looks nice (imo)
however if you don't want to spend much money you can go for a plastic reservoirs with a billet aluminum lid. oberon makes one but you'd have to get both reservoirs of the same size as they only make a lid for a brake reservoir
other companies make these lids but i've forgotten. surely someone else will remember