Web Master:
The best advice I can give is not to buy a cheap one.
There are plenty on the market, usually electric, under $350 and claim to do everything.
A decent chipper/shredder will cost you around $700-$1,500 and have two or four stroke engines to drive them.
You best bet is to type 'Plant Shredder/Chipper' into Google, then select the 'Shopping' tab which will give you a selection including photo and prices. Its a little known feature of Google, yet very useful.
However you can also just hire them which is a good solution if you have a big project, then you can do it all in one go.
Below is a regular garden shredder from Kennards Hire.