I just bought the Mavic and Consequently have a P3 hardshell case and spare battery for sale.
Both in mint condition - both bought jan 2017. Case has been no further than the fields at the back of my house 6 or 7 times. Battery has been charged 14 times (have Go App screen shot to prove) and is a genuine DJI item from Jessops. It has never been discharged below 20%. Say £75 for battery and £30 for case if interested + postage. Can supply copy invoices amd pics.