Found a impeller for Super 5 (Mercury MK6)on feabay for under $15
http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=330579970081&ssPageName=STRK:MEWAX:IT
http://www.marineengine.com/parts/sierra_marine/catalog.html?http://www.marineengine.com/parts/sierra_marine/index.htm?gclid=COrr8dnd46kCFSN5gwodJH-naw
this one is from sierra marine for around $10