i use following,
YSL Opium
Boucheron Jaipur
Burberry London
Diesel Fuel For Life
Bvlgari Man
bought them from many places, like Amazon.com, local mall [Central], Fragrantica.com and Unboxed.in. i would recommend Unboxed.in if you don't really care about packaging. of course, you would have to read about places where you could buy authentic perfumes. try to experience/smell them at malls as much as possible. once you get hang of it - you can make informed decisions/purchases. just like audio equipment you can't decide without auditioning, but you can always make a informed choice after some experience as you may not be able to audition everything. also i suggest you browse basenotes.net - it is a forum dedicated to perfume discussions.