Cheapest flying option from Eastern Europe to West Coast America, anyone?

I don’t have much international traveling experiece so can’t suggest the most helpful advice. But after a month searching for a cheap airfare from Sarajevo to San Jose, California, USA, I came up with cheapest option:
From Dusseldorf, Germany to New York: $205 with LTU, booked through cheaptickets.com, through search engine from kayak.com.
From New York to San Jose: $190 booked through Jetblue Airway
In the beginning, I thought that the cheapest flight out of Europe to America were from either London, Paris, or Frankfurt and based my searches on those critieria. I came upon air deals ranging from at least 500 to 2000 dollars for just one-way tickets.
Finally I found kayak.com, a super-cool Ajax based web application which provides a super user-friendly experience. I liked kayak so much that I even suggested my boyfriend to mention this website in his master thesis about Ajax technology.
How did I come up with Dusseldorf?
All of the found cheapest airfare flying from Paris, Frankfurt, and other major neighboring cities e.g. Barcelona, Madrid, Rome changed in Dusseldorf. So I modified my departure city.
But why flying from Dusseldorf is cheapest?
Probably this is a major business city with strong tie to a major financially important New York city. This is just a guess though. If you know, please fill me in. And if you know of other cheaper options, let me know also.
Thanks.





[...] A few months ago, I bought an air ticket to USA from Dusseldorf, Germany after many attempts to find cheaper airfare flying out of other major European cities, e.g. Paris, Frankfurt, Barcelona, Madrid, Rome, etc. Most of the cheapest flight out of these cities shared one thing in common: connecting to Dusseldorf before heading to JFK, New York. I started wondering about the importance of the city, about the role it might play in Germany’s economy. You can read my previous post here. Today I got my answer. [...]