Sorry for not posting in this for such a long time... Here is a .png of some mountains. It should be easy for you to use them by cutting them out and using a "Multiply" transfer mode to take the white out. If there is still interest in brushes just let me know and I will make some for you.
I make things big then shrink them to make it look like I can draw :-)
I am always taking requests for items like the ones in this thread.
Free for any type of use.