public function sanitize_cost( $value ) {
		$value = is_null( $value ) ? '' : $value;
		$value = wp_kses_post( trim( wp_unslash( $value ) ) );
		$value = str_replace( array( get_woocommerce_currency_symbol(), html_entity_decode( get_woocommerce_currency_symbol() ) ), '', $value );
		// Thrown an error on the front end if the evaluate_cost will fail.
		$dummy_cost = $this->evaluate_cost(
			$value,
			array(
				'cost' => 1,
				'qty'  => 1,
			)
		);
		if ( false === $dummy_cost ) {
			throw new Exception( WC_Eval_Math::$last_error );
		}
		return $value;
	}