Pawn shops? Talk to a guy named Seth=L, tell him I sent you
If you could save up a bit more money...the B&W 686's sound good when they are positioned correctly, and have quite a bit of bass for small speakers (see not requiring a subwoofer perhaps). However, the bass is slightly boomy and overextended compared to the 685's which feel more natural and make less of an initial impact. I've personally listened to the 686's and they are good speakers, especially for their very small size. You could always make them surround speakers if you ever upgraded

But, I've also listened to the 685's and although a put-off at first, (first the speakers were wired out of phase and the bass wasn't as pronounced as the 686's) they are more true to the music and fill the room with sound better than the 686's.
I would also recommend the Paradigm Studio 20's. I've seen them used for around $400, and they are defiantly quite good performers. However, it's been about a year since I've listened to them, and construction/drivers change, but they still might be the same. I would assume and hope so
The ERA D4 is even smaller than the B&W 686, but puts out a surprisingly good, clean sound that fills the room. The only problem is that it does not have much low end at all. And I think they are $600 as well.
Staying in budget:
Speakers that I've heard of, but not heard:
Axiom M2
http://www.axiomaudio.com/m2i_main.html
SVS SBS-01
http://www.svsound.com/products-spks-sbs01.cfm
I don't recommend Bose or White Van Speakers.
Example:
http://sfbay.craigslist.org/sfc/ele/498523350.html
http://www.bose.com