While collectible auctions offer bidders the opportunity to obtain interesting, unique lots at competitive prices, the bidding process is always a two-way street. Nothing makes that more clear than taking a look at some of the most expensive collectible items ever sold. While the items listed here are outside the price range of most folks, anyone can become an auction expert with our year round collectible auctions. Make sure to log on to www.iCollector.com to start building your collection today. Now, with no further delay, here are five of the most expensive (and interesting) collectible auction items ever sold:

1) Francis Bacon Triptych
A triptych, a piece of art displayed across three separate mountings or canvasses, originally done by Francis Bacon sold at auction in 2013 for $142.4 million in New York City. The auction, which featured over ten minutes of active bidding between seven high-powered clients, generated the most expensive price tag ever for art sold at auction. Attended by a number of art collectors from around the world (shopping for either their own collections or those of clients), the auction was ultimately won by William Acquavella, an art dealer residing in New York City. The piece, entitled "Three Studies of Lucian Freed," features Bacon's friend in three different, seated positions. Valued before the auction at roughly $85 million, the closing bid of $142.4 million broke the prior record of $119.9 million, set in 2012 for Edvard Munch's famed "The Scream."

2) The Mercedes Silver Arrow
Who doesn't love a good classic car? For some collectors, though, a Mustang simply won't do. In 2013, one of the rarest cars ever produced was sold at auction for an unfathomable $29,601,500. The car, a 1954 Mercedes Benz W196R, also known as the "Silver Arrow" has quite the history. Manuel Fangio, one of the greatest Formula One drivers of all time, won the F1 series five times. In 1955 and 1956, when he raced for Daimler Benz AG, his victories came behind the wheel of this machine. The car won 9 of the 12 races it was entered in during its professional lifespan of 18 months. Two of these wins were world titles claimed by Fangio​ himself. Of the 14 Silver Arrows ever produced by Mercedes, only 10 remain intact. Three of these ten are in museums, with the remaining six in the possession of Mercedes Benz. The rarity of the vehicle helps explain the lavish price tag. 

3) Marilyn Monroe's most famous dress
While it may be hard to imagine for some, there exists an incredible market for collectible clothing sold at auction. On May 19, 1962, Marilyn Monroe delivered her famed "Happy Birthday, Mr. President" serenade to then-Commander-in-Chief John F. Kennedy. For her performance, Monroe was outfitted in a $12,000 dollar dress. Legend has it that the dress was so tight and form-fitting that Monroe had to actually be sewn into it prior to appearing. An entirely unique item, the dress was purchased at auction for $1,267,500 in 1999 by a company in New York City specializing in collectible items.