Does anyone know a good travel agent in the US to organize a ticket from London to Dubrovnik
I have been having a hard time and finding tickets to be expensive b/c of foreign taxes - any advice on buying the tickets in europe and are flights from Zagreb to Dubrovnik hard to come by ?  

It is quite expensive to travel from London to Dubronvnik, like about GBP250. Alternatively you can fly to Trieste in Italy with Ryan Air www.ryanair.co.uk pretty cheaply and catch a bus to Dubronvnik, if you don't mind the 15 hour journey!!  

The best flight u can find is through Croatia airlines or Atlas travel agency. They sell tickets for local airline, which is cheapest one u will find. Get the phone number for Atlas travel agency, call them on the phone they have best fairs, also u can check out website for croatia airlines at www.croatiaairlines.hr.
Good luck!