First and foremost, congratulations on a wonderful piece of art. The realities of accounting should not distract you from the fact that the project was a success and enriched people's lives.
Although you paint a pretty bleak picture of the finances, as others have pointed out above, this does not reflect the economic reality.
The typo impacted your profit margin significantly - without it, you would have had an additional $7k and a margin of 19%.
But this is only a side show. Even if you had made 0% on the posters shipped to the Kickstarter backers, the 800 posters remaining represent a book value of $96k. (Less a few hundred dollars for storage).
Assuming you can sell at this price, your three years work will be amply remunerated for a part-time project.
In the end, Kickstarter functioned as it should. It reduced your risk by providing a pool of known buyers and left you with the infrastructure for approaching your market. That market is your final reward.
Right, but you are left with an extra 800 posters, which have already been printed and just have to be shipped. Had you just done a printing run to fulfill the commitment to the backers, you'd be left with more profit from the project at this point, but instead you've been paid less, with the potential for more revenue with higher margins. More risk, (potentially) more reward.