Dutch Auction -

the buying or selling of Multiple items which are exactly the same.

This link is arrived at by typing in Dutch Auction on the eBay  help menu

http://cgi6.ebay.com/ws/eBayISAPI.dll?MfcISAPICommand=SearchHelp&requestEncoding=1&searchString=dutch+Auction&submitButton=Search+Help+Pages

The links shown on this page  (and below) will lead you to the following information:

Web Site – eBay page  for details on Buying Multiple items

http://pages.ebay.com/help/buy/buyer-multiple.html

Web site – eBay page  for details on Selling Multiple items

http://pages.ebay.com/help/sell/multiple.html

Web site – ebay page for calculating insertion fees

http://pages.ebay.com/help/sell/fees.html

Web site – ebay page for calculating Final Value Fees

http://pages.ebay.com/help/sell/fvf.html