http://www.chiefsplanet.com/BB/showp...6&postcount=10
That might help. It was aimed at a person looking for tickets to the Steelers game (in Pittsburg), but the info should still basically apply.
http://www.kcchiefstickets.net is a new site that seems to be decent, though people still seem to be asking for pretty high prices.
If you're looking for a broker, check out stubhub.com.