I was given this link by the caching gods and have myself purchased a few items that are going to be used to hold an ammo can under a park bench....:)

http://www.wondermagnet.com/dev/main.shtml
  ----- Original Message ----- 
  From: Kevin 
  To: listserv@azgeocaching.com 
  Sent: Thursday, January 30, 2003 10:00 PM
  Subject: [Az-Geocaching] Mega Magnets


  I used to buy a lot of what we called "Super Magnets" from A&B Prospecting in Tempe. Drop one and it will break into a lot of small clen magnets that hold about 8-10lbs each. I bet Wally still keeps them in stock.