It is a easy thing to modify it to add vibration. I got some vibration motors from cell phones, but they are rather weak. I ended up using a vibrating motor from a old Playstation one controller. I've used it in my pinpointer since I took it out of the shipping box for the last few weeks on the same battery. One thing that is recommended by all is to replace the cheap HF button with one from Radio Shack for $2 (as the original will quit working right within a few hours of use).
In the PS controller simply take out the phillip screws and disconnect the smaller motor. In the image below it is on the right
View attachment 651872
Then simply wire it inside the pinpointer to the wires coming from the piezo speaker, hot glue it in place and your good to go. It took longer for my soldering iron to heat-up then do the entire mod. Here are
some instructions on how to do the mod with pictures (I didn't find any on this forum).