I bought a couple off of ebay for like 5 bucks, I run one on the front flap of my apc and one on my left side. The one on my front is pretty useful if I need to take my gloves or goggles off I can just hang them on the grimloc. The one on my side just carries random things that look good ( e-tape, chemlights etc.). Overall i'm pretty happy with them, I would say $5 well spent.
Grimlocs are one of those things that is invaluable on any kit. They're so helpful it hurts. I've used mine to hold down my hydro tube, my PTT wires, my keys, my gloves/goggles/helmet, Tape, ID/badges... the list is near endless!