Try craigslist or a local piano mover. Local piano movers are often asked to haul off abandoned pianos and will resell them [1]. This company's stock at the moment is a bit pricey compared to what I usually see, but it's not unusual to be able to get even a baby grand for ~$1,000. The catch is you've got to pay to move them, which is a bit of an ordeal.

[1] e.g. https://www.actionpianomoving.com/used-pianos if you're in the greater NYC area