Yes, ZITHERS is a Scrabble word!

Letter values in Scrabble US: Z 10, I 1, T 1, H 4, E 1, R 1, S 1.

Is it a valid word?

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

a musical stringed instrument with strings stretched over a flat sounding board; it is laid flat and played with a plectrum and with fingers