Stereophile's budget list is one place to start looking. Look at those speakers whose retail is not quite double your budget... more or less. think about what's going to run them, your amp, their specs, weight, the sellers feedback, distance, shipping etc. then pull the trigger.
Personally, if for movies and sing along, I'd try getting a nice pair of monitors & sub first. Def Tech Mythos have been rated well. several others have as well.