4zoranss,
If I was you, I'd be looking at used speakers. That way, you can try them and if you don't like them you can sell them at a minimal loss.
You said that you have a medium sized room. Is this going to be a dedicated listening room or a family room. If you're only going to be sitting 7 or 8 feet from the position of the speakers, you may be better off going with a pair of nice monitors, since you already have a sub.
There is such a thing as having too much speaker.