Why a 3 1/2"? I've never seen anything killed by a 3 1/2 that couldn't be killed by a 3".
What kind of money are you looking to spend?
New or used? Auto or pump?

If you've got the money, a Beretta Extrema 3 1/2" auto in the shadow grass camo is one sweet gun with excellent reviews from all the major hunting magazines. Tell us more about your needs and you will get some help.