By GINIA BELLAFANTE

One day many years ago, a little boy named Tim Burton couldn't play outside. It was raining, so he spent the afternoon watching The House of Usher. So began the director's lifelong idolization of acting's mystery master Vincent Price. Now Burton, 33, has committed his reverence to celluloid in a documentary on his muse. The film -- minus any marketing extravaganza -- will arrive at festivals next year.