So I have a (maybe) unusual one.
I have 3 promotional Duracell Bumblebee Kre-o limited edition HK only release keychains. I only need one, so I want to sell the other 2 (still sealed in plastic wrap), but at a fair price/starting bid.

Pic is of one of the keychains next to a Kreon.

How do I put a base price on something I can't find a selling price for online? I don't want to price it ridiculously (either too low or too high) so I'm open to suggestions.

Apologies if this is the wrong thread to put this in...