take a look at the page I have on powered monitors [speakers].
has some low & high-end stuff. not on their web site (for some reason) is their Pheonix speakers, which are $8600/pair, and are an electrostatic+dual-cone subwoofer hybrid.
powered monitors $300
powered speakers. can use for PC, or for stereo (line out only!) or for keyboard in apartment (not intended use) and have plenty of volume. powered monitors usually have pristine sound for use in studios in the back room. these are the lower-medium end, but not the lowest you can go. Behringer makes some 100W compact $70 monitors listed under "business speakers".
keeps the speakers from rumbling your table & ruining the sound.
Behringer Monitor Speakers 1C MC Business Speakers (100W), available from proaudiosuppliers $40
This can be used as a PC Speaker, though it is not typical. Inexpensive, 2-way passive speakers for A/V monitoring, 5.5" woofer with ultra-light cellulose cone, high-resolution .5" tweeter, High output, high 100-watt power handling capacity for low distortion, full-range output, Internal crossover network for phase-corrected frequency reproduction, Auto overload with auto-reset protection prevents tweeter damage. Note: If these are anything like the other beringer speakers I have at home, they are loud enough to blast your apartment. And the audio quality is pretty decent on these things. Can be used with a keyboard probably or mixer, with the right adapters & such if it doesn't already come with them.