http://www002.staples.com/Catalog/Browse/Sku.asp?PageType=1&Sku=577077
^^^ this is $59 for 10 piece cross cut shredder. I had a 6 piece shredder and it kept bogging down on me so I upgraded to a 24 page shredder for $79. That's a little more than you want to pay, but it also does credit cards and CDs. The link above does CC as well. The one I just got (24 page) does only straight cuts as opposed to the one in the link which is cross cut. I'm not too worried about privacy to that extent.
It really depends on what you need it for and how you'll use it. They have an average use per day sheet count. 50-100... 100-150... etc.