Many official Heroes props and costumes are being auctioned off at http://www.nbc.com/auctions/. Items vary from Tim Sale paintings to Cheerleader uniforms to household stuff half-melted by Sylar's weird stuff-melting power -- these are real items that were part of the show.

The auction started on Nov 19th and runs until Dec 3rd. I also heard that there will be more auctions coming soon.

Portions of the auctions' proceeds will benefit the United Way and its partner organizations.
Main Auction Link (http://www.nbc.com/Shop/auctions/)
Heroes Stuff:
Claire's Teddy Bear Collection (http://nbcauction.auction.seenon.com/viewitem.php?item=597)
Painting of Peter Petrelli Under the Homecoming Banner (http://nbcauction.auction.seenon.com/viewitem.php?item=604)
Sylar's Melted Objects (http://nbcauction.auction.seenon.com/viewitem.php?item=598)
Claire's Cheerleading Uniform (http://nbcauction.auction.seenon.com/viewitem.php?item=599)
Hiro and Charlie's Global Airline Tickets (http://nbcauction.auction.seenon.com/viewitem.php?item=600)
Claire's Manatee Exhibit Brochures (http://nbcauction.auction.seenon.com/viewitem.php?item=601)
Comic Featuring Hiro and Sylar (http://nbcauction.auction.seenon.com/viewitem.php?item=602)
Hiros' Yellow Pages Book (http://nbcauction.auction.seenon.com/viewitem.php?item=603)
Painting of Claire and Zach at School (http://nbcauction.auction.seenon.com/viewitem.php?item=605)
Painting of Claire Bennet (http://nbcauction.auction.seenon.com/viewitem.php?item=606)