Jaran B wrote a review of Metolius T-Nut Bag on June 26, 2013
Familiarity: I've used it several times
The price for 3/8-16 t-nuts varies widely. This price is the second best I've found; you can find them cheaper on Amazon. A couple of local hardware stores had cheap t-nuts for all sizes except 3/8-16. Very strange.
When installing, I've found that using a bolt to pull them into place instead is a better method than pounding them with a hammer from the back side of the wall. So far, I haven't had any spinners or crooked t-nuts.