After Effects might work. It's made by Adobe. It's pretty expensive, but there is a student price. In some ways After Effects is more powerful than Motion, in some ways less. However, Motion has a MUCH better UI.
I'm an After Effects fan, but last time I bought it, it was more that twice the price of Motion. Motion is cool too, but yeah, the system requirements are insane if you just want to dabble (or be portable). AE will run on just about anything.