I picked up this radiation detector, also know as a Geiger Counter, at the Indianapolis Ham fest in July 2004 for $3.00.  I'm am not sure if my unit works correctly or not since I do not have a radiation source to test it out on.  I purchased this mainly for the novely and price. Below are some links for anyone who is interested including a manual and technical information.

    Here is a page from the Civil Defense Museum: CD V-715 Gamma Survey Meter Page
    Instruction manual for the CDV-715: Instruction and Maintenance Manual for CD V-715