About buying cosplay items, you can, but I'd wager to add "only in Japan".
The Trigun crimson suits costs 50000JPY, for example, but I doubt you 
can find it anymore....

As many others pointed out, the funny thing in cosplaying is to create 
your own... it's also the only cheap method.
But it takes so much of your spare time... took me 3 weeks to create a 
carton copy of Herb's armor, and it isn't even good.

Anyway, good luck! 

	 Pierre