eBay

"My house is filled with this crap
Shows up in bubble wrap
'Most every day

What I bought on eBay."

eBay, the web's Bazaar of the Bizarre. Although it acts primarily as an Auction-based website, some sellers use "Buy It Now!" buttons allowing you to instantly purchase the item at "bargain" prices.

It can be a useful way of averting No Export for You, to Keep Circulating the Tapes and - as with everything else on the web - helping indulge your Fetish Fuel. You cannot, however, sell people or weapons. We've tried.

eBay has now become a trope in itself, as the place where heroes can find their Plot Coupons.

Tropes used in EBay include:

Air Guitar: Yes, some really do get sold.
All Animation Is Disney: Either because the sellers are genuinely unaware, or because they think they'll sell more if they claim their old VHS copies of Don Bluth movies are made by Disney.
And 99 Cents
Auction: The whole point.
Getting Crap Past the Radar: Some exhibitionist sellers delight in uploading nude pictures of themselves via reflections in metal objects they're selling on the site.
No Swastikas: "eBay does not allow listings or items that promote or glorify hatred, violence or racial intolerance, or items that promote organisations with such views." So, you'll have to sell your old World War 2 memorabilia somewhere else.
Read the Fine Print: Some people like to sell boxes for gadgets with warnings like "PSP box, PSP not included". Despite this, people might still pay hundreds for it.
We Sell Everything: Almost everything, anyway. Why steal a traffic cone when you could buy one?
What Did I Do Last Night?: Can happen if you browse eBay while drunk.
Young Entrepreneur: You can make a lot of money by selling.

eBay in media:

The Big Bang Theory: Sheldon sells a World of Warcraft item on eBay. This is, however, a case of Did Not Do the Research, as Blizzard would have banned Sheldon and the buyer from Warcraft for doing this.
The Dresden Files: In a case of Did Not Do the Research, one villain tries to sell Harry on eBay.
Transformers: Sam intends to sell his great-grandfather's glasses on eBay (thanks to a Product Placement deal for the film).
"Weird Al" Yankovic's song "eBay"
In the British panel game show Would I Lie to You?, panelists sometimes have a "Possession" which they must claim as their own (and convincingly argue that it really is theirs when it is not, or vice versa). A common justification is that this was a late-night drunken eBay purchase.
Xkcd with this strip, which is later referenced in the mouseover text of this one.
Jay Leno used to do a segment on his show called "Stuff we found on eBay". He would present a collection of some of the most blood-stoppingly inane stuff on eBay at that time, and ask the audience if it got sold or not.
Joe Hill's novel Heart-Shaped Box is a curious example. The main character buys a ghost from what the book describes as "an online auction site, not eBay, but one of the wannabes".
In Finding Nemo the aquarium fish list where they came from. For the Starfish, that's eBay. Except that live animals aren't allowed to be sold on eBay, making this a case of Did Not Do the Research
In Toy Story 3, Hamm suggests to the group that they look up what they're going for on eBay, because, after all, Andy doesn't want them anymore.
Yellow Eyes has something of a Running Gag about how it's amazing what you can find on eBay, including an alien medical device used to build a physical body for an AI and a mate for a formerly hostile Posleen advising the humans after the war.
An early Sequential Art storyline had Pip getting carried away in an auction for a rare comic book issue, getting a winning bid of several thousand dollars that he couldn't afford to pay. In a case of Did Not Do the Research, to pay for it he auctioned off Scarlet, a squirrel living with them, on eBay.
The Amazing World of Gumball features JUNK