turbosquid.com is a true treasure, especially when you list the cheapest models first:
http://www.turbosquid.com/Search/Index.cfm?INTFILETYPE_3=0&INTFILETYPE_1=0&BLSHOWCATEGORYSELECT=TRUE&INTRATINGCOUNT=0&ISTSEARCHKEY=helicopter&INTFILETYPE_2=0&INTCATEGORY=-1&INTBUNDLEID=&ISTINCAUTHOR=&ISTEXCAUTHOR=&FUSEACTION=ProcessSearch&FLTRATING=0&DATEBEFOREPUB=&INTMEDIATYPE=2&STGBOOLEAN=L&INTMAXPRICE=&STGTYPE=&DATEAFTERPUB=&BLSEARCHGAMEREADYONLY=FALSE&INTSTARTROW=1&ISTEXCKEY=&INTMINPRICE=&stgAD=15J244404040441&stgOrderColumn=A5&intSortOrder=1&blViewType=1&blViewTypeTip=y&intMaxResults=50
http://www.turbosquid.com/Search/Index.cfm?INTFILETYPE_3=0&INTFILETYPE_1=0&BLSHOWCATEGORYSELECT=TRUE&INTRATINGCOUNT=0&ISTSEARCHKEY=helicopter&INTFILETYPE_2=0&INTCATEGORY=-1&INTBUNDLEID=&ISTINCAUTHOR=&ISTEXCAUTHOR=&FUSEACTION=ProcessSearch&FLTRATING=0&DATEBEFOREPUB=&INTMEDIATYPE=2&STGBOOLEAN=L&INTMAXPRICE=&STGTYPE=&DATEAFTERPUB=&BLSEARCHGAMEREADYONLY=FALSE&INTSTARTROW=1&ISTEXCKEY=&INTMINPRICE=&stgAD=15J244404040441&stgOrderColumn=A5&intSortOrder=1&blViewType=1&blViewTypeTip=y&intMaxResults=50