TinEye provides a great way to "reverse" search by image (i.e. upload/transload an image and have multiple possible sources of that image returned as results.)
Since screen-scraping is messy and unreliable, I'm looking for a free API/library/web-service that could offer the same (or similar) reverse-image search function.
At present, TinEye offers a commercial API, but since I'll only be using the service for small personal projects, it's hard to justify the cost of the service (the lowest being 1,000 searches for $70 USD).
Is anyone aware of such a free service? Or is there a simpler way to approach this (programmatic solution; any language)?
I understand that this is a tall order, and submitting the question is really only a last resort in the hope that there is some solution.
Example image search is 99designs' StackOverflow logo competition entry by wolv