Go to a really good painter--& I mean really good, someone that has been doing this for 20 plus years. They will have the eye & expertise to mix you a small batch, they will have to start then modify it slightly a couple of times to get it spot on --but thats your best bet---far better then just going to a paint supplier & telling them what you need-& they can never get it right. --depends on how close you want it it be.