I bought a set at harbor freight since I started doing my stuff - they work OK and do provide some assistance...
They are like $5 or $6 for 8 or 10 of them (at HF) - way cheaper than the other places I looked at. I can get a part number off them when I get home tonight if that helps.
If you can get to the back of the panel you are welding - they can be helpful - several of the areas I have tackled I didn't have clear access to the back of the panel to use them...
Found the part number [44751] -
http://www.harborfreightusa.com/usa/...o?itemid=44751