50 second credit animation

Looking for a 50 second hand-drawn sketch-like animation over credits and live action footage. We have just finished shooting a short film and are looking for animation to be done on the credits. Two people are kissing on a patch of grass and we would like a sketch of a palace/castle interior to be gradually grown and drawn around them as credits roll, in a very hand drawn style, lasting about 50 seconds. We would also rather agree on a fixed price rather than a price per hour. This is a student film.