Cumberland costs a little bit more than Black but not much more.
The cost for a new stem is in the labor to do it. It takes just about as long to make a new stem for a pipe as it does to make a whole pipe, so the cost for a new stem to be made is in the labor.
It is a labor of love too. Check it out, how many of you would work for $5.00-$7.00 an hour? Thats about what a pipemaker makes when making a replacement stem. It is even less if there are silver bands on the shank end, (the silver has to be removed to fit the stem) or exotic woods on the stem itself.