Mancini has for $29.95.You can make them cheap too out of u bolts and flat
steal.Still using vice-grips doubled up myself,spent all the money on the car,none left for tools.
I made mine with 2 pieces of 1/2"x4" flat bar and 4 bolts. Clamp onto the bar and beat with hammer. Cost was time to scrounge and torch up some scrap. Probably $10 in metal and same in gas if I had to but the plate new.