Be prepared to pay $35k or more. Nice choice. They all have the same engine, with the 333hp, so just look fo rthe best you can buy with whatever money you set aside. Lower mileage and accurate service records are usually good signs. I would stay away from modified vehilcles. If you want mods, you are better off doing them yourself. Get a Carfax account, and check in here whenevert you find prospects. I don't have specific experience with the e46 m3, so there isn't much I can add. (e46 is teh chassis designation for BMW 3 Series vehicles in the model year range you specified).