Wendell Marshall was born in 1920.

Marshall Wayne died in 1999.

Wendell Marshall Thomas has written:

'Toward a more democratic social order' -- subject(s): Economic policy

'There is but one individual' -- subject(s): Religions (Proposed, universal, etc.)

s/n 24050 would be prior to 1900 (those s/n's started at 26,500). Marshall & Wendall started their business in 1836. I would guess that would make your piano manufactured around 1880-1890.

Like anything else, the price depends on the condition and many other factors. See related links for a little history and examples of Marshall & Wendell pianos selling for $9,500 - $25,000.