Dkzzzz, you are dreaming in colour if you think you will find speakers with flat response from 20Hz to 50kHz at the price you mention.
Even if a manufacturer claimed 20Hz to 50kHz in a spec sheet, with no qualifying parameters (+/- 3dB, for example), it would only be meaningless bafflegab.
In the real world, a speaker with flat response +/- 3dB from 40 to 20KHz is exceptional enough. However that spec tells you almost nothing about what it sounds like in a store, and less about what it sounds like in your system.
Your question shows you need to educate both your mind and your ears.
For the ears, go talk to some dealers. Tell them what you want and ask to listen to some speakers in your price range. Take notes on how the music sounds.
For your mind, there are a couple of good books here. Start with the one at the top.
http://www.uhfmag.com/Books.html
Even if a manufacturer claimed 20Hz to 50kHz in a spec sheet, with no qualifying parameters (+/- 3dB, for example), it would only be meaningless bafflegab.
In the real world, a speaker with flat response +/- 3dB from 40 to 20KHz is exceptional enough. However that spec tells you almost nothing about what it sounds like in a store, and less about what it sounds like in your system.
Your question shows you need to educate both your mind and your ears.
For the ears, go talk to some dealers. Tell them what you want and ask to listen to some speakers in your price range. Take notes on how the music sounds.
For your mind, there are a couple of good books here. Start with the one at the top.
http://www.uhfmag.com/Books.html