This script converts the files of the selected tracks in iTunes using an encoder of your choice on-the-fly (restoring your Preferences-set encoder afterwards). The newly converted files are then moved to a new location of your choice, and their tracks removed from iTunes.
OS X 10.6.8 or better.
Also see ConvExp to Album Folders.
Re-associate batch of dead tracks with files from selected folder
Create a playlist for each entry of a specified tag
Exports and then re-imports selected tracks' artwork
App displays files in iTunes Media folder which are not in iTunes library
Export files of tracks in two or more playlists to single folder
Fill a playlist with user-set number of randomly selected full albums