room treatment panels on the way!

^ not bad ... thats about what I just dropped on treatment too, and for about the same amount of stuff, you probably got a little bit more ... just wanted to make sure I didn't shoot myself in the foot too badly ;)
 
I have nothing for acoustics in my room it is a boxy style 3x3 mts but on my left I have a big "all wall height" window. Which is the cheaper and simplest thing to do or to buy to get a better acoustic ?