Currently there are 3 existing applications for flickr synchronization: bulkr, FlickrSync, and photoSync.
You can learn more here: http://www.flickr.com/services/apps/tags/sync/
Two of these are open-source: bulkr and FlickrSync.
But the best application is closed-source: photoSync.
The purpose of this project is to create an open-source application better than photoSync. You can use the code from bylkr and FlickrSync or write new code, it doesn't matter.
One additional feature I want is sub-folder synchronization.
The budget for this project is very low since everything is open source. I only want to spend a few dollars. It is a good practice project for someone looking to earn ratings and to have a portfolio project that can be shown legally to future clients.