If you look at the pics of my bike in the "Who drives what?" or the "Show us your motors" threads, you will notice its fitted with a standard Aprilia late 2003 model exhaust can, a sort of "bronze" finished one.
@£900 to purchase from a dealer.
Got it for £25 on fleabay inc delivery. It was removed from the owners bike when new as he had a twin Akrapovic set up ready to go on when he bought the bike as brand new.
It still had the clear "shrink wrap" on it for protection during the shipping of the bike in the crate, so it hadn't even been run.
Thats a bargain in my book.
Also, not really a "part" as such, but motoring related:-
Set of Dainese "K" 1 piece race leathers. Used half a dozen times, again, snaffled on fleabay.
New-£1200.
Grabbed 'em for £120. Result!!!.