Go to the Collectibles section of eBay (http://collectibles.shop.ebay.com/) and pick any subcategory that looks interesting to you. Find an auction that is just about to end and bookmark it. When the auction has ended, return to the auction page and click on "Bid History." (If you have an eBay account, you have the option for searching "Completed Listings.")

Use the bid history to construct a demand curve.

(You will have to "reorder" the bids a bit to figure this out. Try to figure out the maximum price that each of the bidders is willing to pay, and then use that information to construct the demand curve.

It can be a picture that you made with a program like Excel, or it can be a hand-drawn graph that you scan or take a picture of with your phone. Also please enter the eBay item number in the text box below. I need the eBay item number so that I can check the bid history to confirm your data.