i know MIDI music is a bit old-school (thats why we're all here

im looking for a long tune that lasts about half an hour or longer, that changes styles (dramatic, sad, quiet, loud, etc.) but is intended just to play along in the background as the player plays the game. by MIDI, i mean im just looking for a .mid file that will play on all PCs. i have screenshots of the game which may help give a feel for what music may best suit.
naturally i intend to legally 'own' the music as it were. im not expecting this to be done for nothing, but the game is my own and im on a limited budget.
does this interest anyone?