Once LO outgrew it?

We're done having kids so we either will need to donate it or sell it. The same car seat on local listing sites goes for $100-170 but I don't think I would feel right selling it for more than $20. DH said if someone buys a second hand car seat, they probably need it more than we need extra money so he wants to list it as free - but then people assume something is wrong with it! Places like goodwill won't accept baby gear.

Did you sell yours? Save it? Donate it?