I think it quite is ridiculous to have to spend that kind of money for a couple of pieces of felt. I can remember that a similar felt is also under the automatic transmission shifter cover. That felt gasket is NLA, and if your felt is similar to that, then great: don't dye it but split it up big enough for these pieces! I would want a piece of that as well.
There are a few other places where black felt is needed, such as the forward wall of the softtop compartment, the steering wheel, around heater vents, etc. The felt piece above the steering wheel is sown over and has a piece of plastic piping in it. I found a local fabric shop that had quite a selection of black felts that come quite close to the originals in most cases, so that was the route I went. The greyish felt is a bit different, so why dye something if you don't have to?
Just an FYI, and not meant as a criticism to those folks who are dead set on having "original' Mercedes supplied new black felt in certain areas where noone would ever look unless the car is taken back apart.