I think quality is a relative term.........it can be measured in many ways, in terms of quality based on SQ first and foremost? Or actual BUILD quality(furniture grade or just laminated mdf boxes?), aethetics? Or obviously a combo of all 3? Also, are you stuck on towers, or have you thought about doing a higher quality set of monitors in combination with a sub or subs? This type of combo has a multitude of advantages, big one being "sound quality" and optimal placement potential.
You definetly don't need to spend $3k for a top notch speaker though regardless.