Well after moaning about it the other day I finally got my hands on MUA's Crackle polish.
This is the blue one, called Quake
The purple one is, Broken Arrow
They don't dry and crackle as quickly as the Barry M Special Effects. However you can see they they do crackle and give that usual shattered effect.
MUA Quake Polishes come in six different shades, and even though the shelving says it is £2.50 it is actually £2.99. Something I have mentioned to Superdrug and am awaiting a response.