Poorfishy... I just adore Christopher and I definitely believe you could fetch a higher price. I haven't sold any puppets but I do have business selling cloth dolls and evil creatures. I was notoriously bad at pricing primarily because it felt bad making money from something I do more for fun and because I always see the teeny flaws other people don't notice/don't care about. I was put on the straight and narrow a couple of years ago by a fellow seller and now use a similar calculation to the one Shawn outlined above. I think the key is targeting your product to the right market. There are people out there with ridiculous amounts of money that will pay for a one off deign if you can find them. As an example (and I need to say this is the exception) I created a dragon last year from Calico which I painted. He was cool and all and very large, but nothing I would write home about. I would have priced him at about $200 just to cover my time (materials were next to nothing and internal skeleton was constructed from donated wood) however I chanced upon a gallery owner that wanted some 'different' stuff in her gallery. He sold about 3 months later for $650. I would NEVER have imagined asking that price but she knew her clientele well and what they would part for. Prior to that, I had featured him at a local craft expo and whilst there were plenty of offers, the highest was $150 and I chose not to sell. I guess I had the luxury of declining the offers as the Lair is not my livelihood but a hobby that generates some additional income.
The zombies are so incredibly unique. My dolls and creatures are of a similar dark vein and I've found there's a real marker in dark art forums. It's moving away from your art exhibition but you'd make a killing online and fetch decent prices if you advertised to the dark, twisted gothy emo kids out there!

Believe me, they are cashed up! Just a thought.
Christopher really appeals to me and I would certainly pay more than $150. I hope you find a buyer and a price that recognises the talent and time that went in to creating him.