I want to purchase the warcarft 3 and Frozen Throne (expension) key to
play online on battle.net. I already have the game just looking for
the orignal key. From where I can purchase the key online so I wont
waste my time in ordering and waiting for my package.

try http://www.playground.ru/cheats/1111/ ,
there choose download.

Really there is no way to buy a key without first buying the game. 
You could try a keygen from one of the popular cracking sites, but the
chances of it producing a key that will be valid on battle.net are
very low.  I suggest you go buy a copy of the game or try to find a
copy on ebay, it's probably the only way of getting a key that will
definately work

There is a website where you can buy keys, being starcraft keys or
warcraft 3 keys. Currently I am not aware of the person running the
site to sell The Frozen Throne (Warcraft III Expansion) Keys if you
are looking for those.
Currently he is selling 1 Warcraft III Keys working for $3. The
website is http://buykeys.tk
So far I have heard he is reliable.