I would bet you a good sized bet that you won't find anything better for the money than the likes of the new Energy C-1's for $299/pr retail!!!...and that includes more expensive stuff at $300 used!..or more!
However, if you can afford the C3's, they have better bass, and are $499/pr. These speakers are too new to to be found used however, unless you local chain store has them as returned openbox or something.
Anyway, you can also find a used pair of Energy C-2's, that are older models, at around $200=300 range used(retailed $600 new), and these all sound great as music/HT speakers!
I say this, and I've owned some mondo expensive speakers over the years, and none is as exciting for the money as these new Energy bargain speakers!
If you have a large room however, you might want to find some DiAppolito configued speakers (Drive/tweeter/driver) speakers to use to control room refections and focus a bit. Otherwise, you'll love the Energy Conneiseur series speakers, trust me.
They are dynamic, open, pretty decently detailed for the $, clear, uncolored, and great treble and midrange. I've had quite a lot of mid priced monitors come through my means over the years, includng B&W 600 series, Tannoy MX series, NHT 1.5's and Zero's, and others. Thus far nothing at that sub $600 price range new is as good as what Energy's C series is offering. You might want to go give em a listen.
I also know of someone who still has a pair of new C2 Energy's(Stereophile recommended as borderline Class B/C) new inthe box if interested!..it's thought.
Anyway, good luck.