COMIKET, OR ITS WESTERN COUNTERPARTS?

Have you ever heard of Comiket? it is basically a huge 3-day indie event in Japan, right before new years. It's quite old already (I think 40 years old), and in this event people sell and buy indie comics, games, merchandise, etc. as well as cosplay and stuff. But the real cool thing is the large emphasis on the indie market, it's pretty healthy and cool! It's awesome to tell the truth. I've long wanted to do something similar here in my home country of Brasil, though I do not know how would I approach it. Anyway, what do you think of these kinds of events? Have you ever been to comiket? Is there anything similar where you live? =D