there isn’t many options in your price range I’m afraid and probably none in a full range as in 20-20khz you’d be doing well to find something 40-20khz.
used Klipsch is your best bet for most bass i’d think at $500 you may find a MK1 or 2 in the ones I mentioned above.
you may be better off doing a near field set up like one of the guys above was suggesting. so get a nice set of desktop speakers to go with your amp.