Cost to treat a room?

Are you making the panels yourself or buying ones already made ?

If you were to get ones from this site:

http://www.gikacoustics.com/gik_242.html then its just a matter of figuring how many you think you need and then doing some simple math( this site does the total for you ).

What makes you think you need to treat your room?

What does it cost? Well, doesn't that depend on what your room needs? If you can't define what problem you are trying to cure you are getting ahead of yourself to assume your room will just sound better by using commercially available treaatments. If you are not careful you could just end up spending a lot of money for the wrong stuff and end up with a room that sounds worse than it does now. And, to make matters even more interesting a lot of potential or real problems can be resolved by domestic furnishings strategically placed and or speaker set up.

Think it out................

$700-900, assuming you buy used. As newbee remarked, the challenge is to find out what the problem is. Lastly, every room needs to be treated as perfect rooms only exist for perfect people, all can be improved.