clean my fuel tank? (newbe)

so any idea why these tanks differ in price so greatly?

http://compare.ebay.com/like/170529106205?ltyp=AllFixedPriceItemTypes&var=sbar&rvr_id=160075100186&crlp=1_263602_304662&UA=M*S%3F&GUID=f8ad81cb12b0a47a2ed1b1b1ffc9e8cc&itemid=170529106205&ff4=263602_304662

http://www.1aauto.com/1A/Gas-Tank/Dodge/Dart/1AFGT00074/315444?utm_source=google_base&utm_medium=comparisonshopping&utm_campaign=gb_api_nobr&utm_content=FGT

http://www.rockauto.com/catalog/raframecatalog.php?carcode=1087961&parttype=6268&a=FRc1087961k17123-2506034

can buy 2 of the low price for price of 1 high price