no you can. i think these files would be in base\sound.zip
get rid of the ~w at the front btw. the file you're looking for will look like "c_buysell.ogg".
I was thinking of adding a cash register sound to midairs for my T:A config release.
Like this (can't for the life of me find a high quality one) https://www.youtube.com/watch?v=Wj_OmtqVLxY