I am an avid airgunner and know a few things about them.
The truth is, as with centerfire rifles, when buying a pellet gun it is almost impossible to get a bad one. As long as you stick with name brands.
Beeman, Gamo, Crosman, Daisy, Crosman, all have good .177 or .22 cal rifles in that price range.
If I had to give you one recommendation, I'd say the Gamo Whisper, it is quiet, accurate, and reliable.
I have a .25 caliber Theoben and it does the trick for me, but then again, it is more than $150.
I also suggest you mount a scope on it, airguns are very precise weapons that require good optics, more good news is since airguns are only good to ranges out to 50 meters or so most scopes will do the trick, just make sure you use an AIRGUN scope, not a regular rifle scope.
Let me know if you have any more questions, like I said I love this stuff.