My own personal uneducated opinion is that in that condition, I would think it's worth $350-$400. Whether you'd get that much or not is another story. There's nothing to restore on that trike, and to do anything to it would only hurt the value.
I'm not knowledgeable enough on the subject to give you a date. Post it on the CABE in the tricycle section. Someone should be able to help with that, or at least point you in the direction of another site that deals with kids riding stuff.
I don't know how many people collect trikes, but that is the kind a collector would just ask you to name your price. So I think that Dave's $350-400 price is way low. You have a real gem there. Gary
No sign of any tire valves and in the photos, I can only see light through every other link in the chain. I've seen worse examples brand new on a showroom floor.
$350 does seem high but the catch is: it needs NOTHING. I have another Skiptooth Colosn trike & trying to restore one, you would be way over $500 to find all the right parts, paint & decals. Then it would be still restored.
The little trike is cool & for the $ I'm easily pleased. I think $350 was a steal.