In reply to Joshua Steele.

Mostly it's about patience. Know that they know nothing about typewriter pricing and that they're just trying to get as much as they can for something they probably know nothing about and haven't used in decades. Showing them actual sales/pricing on auction sites like ShopGoodwill.com may help. Make what you think a reasonable offer is and let it sit. Then check in a month or so later and they'll realize that it's just sitting there overpriced gathering more dust.