This may not have big sensor. All p&s have sensors of the size of nail of last finger. DSLRs usually comes with larger sensors (hence expensive). Full frame DSLRs come with 35mm sensor which is of the approx size of matchbox (hence pretty expensive).
Its impossible for a bridge camera to have sensor bigger than this as in this case the p520 has an equivalent focal length of 1000 or 1200 mm at full zoom, which will make a very big lens if bigger sensor is used.
Superzooms have this negative property
You may get it cheaper at ebay.
Almost Every superzoom of any make be it canon, nikon, sony, fuji etc etc has full manual controls.
Go for the brand you are comfortable with.
The canon sx150,160,170 may save you a lot of money.