Nothing.
I have just escalated to a PayPal claim. But it looks like Atomic Pop has gone the way of the dodo, the Edsel, and the Bay City Rollers.
So, whatever is out there in the wild is apparently it. It'd be a genuine collector's item if anyone actually gave a crap. Rarity does not make a collectible, desirability does.
Still, it's my first comic book writing to make it into the shops, and we sold almost a thousand copies. Given the market and the economy, I think we did pretty damn good there.