Yo Volley-Ball:
In the price range you mention, putting E-bay aside, you are looking at Yorkville passives or KRK ST8 passives.
The ST8 by KRK have 8" woofers==I have a pair and they are nice. I had Yorks prior and sold them in two weeks.
I don't deal with E-bay because there are too many possible problems.
Used gear? If you can buy it from a friend and can hear it and test it before you pay, that's a good deal.
To give you an example, one of my vendors offered to send me six different mics to try; I could then select the one I liked and pay for it and RETURN the other mics. So, it is like an audition without driving 200 miles in my case.
I don't think E-Bay works like that. And, before you flame me, E-bay has some good deals; however, I don't care to deal in an arena where so much lixiviation of product is entertained. [What did he say?]
So, you can check out the products I have mentioned or look for others. If you can let your ears hear before you pay, you'll be OK. [Nice Wheel of Fortune Rhyme Time.]
Green Hornet