Ebay is a definite classic in that category, you can find almost anything (plus it's available in many countries all over the world). There is also Amazon Marketplace, albeit it is not that widely available. Lesser known auctions sites are eBid (a sort of independent ebay) and Ubid. There's also ioffer, which allows you to place offers on larger quantities of items (beware of imitation designer brand items though). It can also be interesting to seek local, smaller, auction platforms (for example: The Netherlands has Marktplaats and Belgium Kapaza).
There are many online auctions for products which range from cds to houses and cars. Sites such as eBay are very good for auctions and is a reliable site.
Check out eBay motors.
A good place to sell handmade bags is on eBay where they can be placed into online auctions and seen by millions of people. Other good places include markets and Gumtree.
Online auctions
"If you're looking for Avon bottles, online auctions are a good source. However, garage sales, and estate sales may be better sources."
I like to go to eBay for online auctions. While there is never a guarantee that sellers are honest people, eBay does have a good policy that will get your money refunded if you are ripped off.
Cricket memorabilia can be purchased online at ebay. Sports memorabilia stores and auctions are also good places to look. An antique store may also be a good place to look or even craigslist.
Estate auctions are good places for finding used farm equipment for sale. However, the best estate auctions that have used farm equipment will be in rural areas away from major cities.
You can find great deals on cars at auto auctions or online auctions, like ebay.com. You can also check craigslist.com or autotrader.com.
You can get a Wii online for a good price at eBay. Sometimes at Amazon. You should compare prices online. Check classiefied adds and penny auctions, too.
Haulmark is a great company if you are looking for top of the line. However, many places have local auctions and trailers are common at farm auctions and such. A used trailer is often just as good and much cheaper.
There are a number of online sites which contain information about seized vehicle auctions. The web domain "PoliceAuctions," for example, is a good resource.