Where can I find a magnetic locator or a locator to find aluminum in the ground.

Magnetic Locators will not respond to aluminum.

This site offers metal detctors that do find aluminum.
http://www.dixiemetaldetectors.com/security/fisherironlocators.htm
Ronnie Dugger_Dixie Metal Detectors, Jackson, Ms. 39211
Ph: 601-952-0581 or Toll Free (Order Only) 1-888-467-4332
E-Mail DixieMD@jam.rr.com

The Fisher metal detectors  specially designed for finding buried or
paved over valves, boxes, or manhole covers, or any other concealed
metallic object. It also locates targets made of aluminum, brass and
lead.
Prices range from $350 to $600.

I was able to find the locator I was looking for and had it here in
out office within a week.  I would reccomend dixiemetaldectectors.com
to anyone who is in need of a special metal dectector.

I'm not an official google researcher for google answers, but if you
are looking for a metal detector, you might want to look at
http://www.metaldetector.com/ http://www.fmdac.com/. The first is an
online store that sells metal dectectors, and the second is the
homepage of a federation of those interested in metal detecting, which
looks like it might offer some useful advice on recomendations.