Air dry clay sculpture falling apart over time
Fine structures like the fingers of a hand are always problematic, no matter how cheap or good the clay is.

The general recommendation is to build an inner structure (like a skelleton) from a more stable material and coat it in clay. For your particular case of modeling a hand I propose making fingers from rolled up aluminium foil or thick aluminium wire.

Start making aluminum fingers that are longer and thinner than required and coat them in clay. Then make a ball of clay that is smaller than the palm and stick the aluminium fingers in it. Add more clay and model the hand.