I bought a 1972 P D S mint set at a yard sale for $2.00. Sent it to NGC. When they came back there were two nickels I thought were worth the price. The one here: http://www.cointalk.com/t206590/ and this one. The toning doesn't show well in the pics, but it is nice electric blue on the left fading to orange/gold on the right.
The blue toning at the edge. It's a narrow band of blue, running from 8 to 10 on the obverse and 8 to 10 on the reverse. The rims in those areas have a little abrasion also.