Yes, STEPPERS is a Scrabble word!

Letter values in Scrabble US: S 1, T 1, E 1, P 3, P 3, E 1, R 1, S 1.

Is it a valid word?

STEPPERS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a professional dancer
a motor (especially an electric motor) that moves or rotates in small discrete steps
a horse trained to lift its feet high off the ground while walking or trotting

Also: stepping motor, high stepper.