Hi Marksman,
Yes we do replace all sorts of nuts, Edder will tell you I'm the nut mechanic! haha! Jokes aside, a brass nut really wears out nut files and overall much more work required than other materials. Do you really want brass for the tone or just the look. If it's the tone, you'll do better with tusq or bone. They are a cheaper option as well.
However if you must have a brass nut, you shall have it for $90. Inclusive of the nut. Tusq and bone would be between 50-70. If the guitar needs to be setup, additional fees would apply. Thanks for the enquiry.
regards,
KC