I went the cheap route and used dried cat food with fish flavour.
Just thrown a few handfuls over board every couple of minutes.
Seemed like it worked. Got some fish. But maybe I would have caught them without the burley anyway :-)

Problem is that the stuff doesn't sink very quickly.
Might be better to put it into one of those burley nets with a rock to get it down to the bottom.

Good thing: cheap, easy and you don't have any stinky mess to deal with :-)
Bad thing: might not be super effective

The leftovers from a day out free diving for pauas and kinas and the odd cray is great berley. Add fish frames/heads/guts from past fishing expeditions. Even the kina shells, cray shells and fish frames/guts can be crushed in a bucket with the end of an old 4x2 bit of wood. The shell actually holds the berley bomb together alot better after its frozen with some dry blood and bone or even crushed weetbix to get that thick slurry mix just right.

Pour the mix into old subway/shopping bags and double rubbish bagged all ready for the deep freezer. Wrap the sub bags individually in paper to stop clumping in the freezer. The paper actually helps with the mess when you peel the plastic bag off to use on the boat but upto you.

Peel the plastic and dump your frozen berley bomb in a old onion bag or sack. Tie a rope on and your all set(might need a rock to weigh the bag down).

Just a thought next time you dump all the leftover fish frames overboard and shellfish guts/shells to the dump or buried in the garden. Beats buying a $20+ berley bomb that just feeds the fish lol