[SuperToast]

What's the best possible sound quality I can get for under $150? 
I'm currently looking at the M-Audio AV-40's. 
Is there possibly a bookshelf/amp combo for that price that would sound better? 

 

[Jonnoh]

for $50 more you can probably find a pair of BX5a's.  Much improvement.

 

[SuperToast]

So the bx5a's are the best i can get for 250?

 

[Jubei]

Don't know about being the best @250, but the BX5a's are certainly better than the AV40 - I sampled both at a shop yesterday and one can easily hear the difference. I ended up with the AV40 though because the BX5a are beyond my budget  

 

[MtnSloth]

You probably already know this; but, if you are looking at powered monitors, you should be "feeding" them line level audio. I mention this as stereo line level outs are not super common on notebook computers.