Get a Bull Magnet moose call. They're easy to use for both cow and bull calls, and brush scraping. They also really amplify your hearing if you hold it up to your ear.

http://www.alaskaremote.com/bull_magnet.htm

Moose calls are pretty simple to do just by mouth, but a megaphone really helps amplify the sound.

Love, Thunder, and Bull Vol. 2 is a great video to learn moose calling.