The Transformers BluRays have some good sequences that will test any Sub, but if you don't have a Sub you won't know what you are missing.
You stated you are 80% movies. In that case I recommend you buy an AVR (I'd go for the Denon AVR-S910W, I have it's predecessor, the AVR-S900W and it's a good unit with amazing flexibility. The AVR-S920W is only $30 more at the moment, and still fits in your budget, so you may want to consider it. )
An AVR will allow you to add not only a Sub, but a center channel speaker, and then surrounds as your pocketbook, and enthusiasm, allow.