i never liked the glass filled nylon spring clamps. i have had GFN fail on me in several other instances.
if you have an ollies near ya , check em out. my father in law picked up a 36" bar clamp (not a bad one at all) for 7$ . its holding my tillering tree up in my latest pictures.
other than that , i use the metal spring clamps that home cheapo had "on sale" for 1.99 . the ones with the little green covers.
-hov