I have a used Well P90, it needs:
a new magazine
a new strap; at least a metal hook that secures it to the rear of the butt stock
A charger for a 650 mAH 8.4 battery
I have a couple of carry straps laying around and a handful of chargers I don't need. If you want, I can bring them to the zombie hunt or some other game you attend and can take a look at them.