Are you talking about just a scent to add to the eggs, or the actual egg cure itself? If your looking for the egg cure, try Ammermans. They're a sponser and have a link on the home page. If its just a scent, Mikes seems to be a pretty good one.
Scrimmy is right. The pure stuff is real strong. A little bit goes a long ways.
Start with a few drops. If it still seems weak( unlikely) you can add a couple more drops later overnite. It will soak in( can't do this on frozen eggs. They can defrost in the fridge for a couple days, then add the anise. Turn the jars a few times for 24 hours to get it to absorb thru all the eggs. And refreeze.). You can also put it in there when you cure the eggs. Just add it to the egg goop before the eggs start to reabsorb the yummy juices.
Mark and the wearing rubber gloves to keep the grease in check dog.
There are those out there (names exluded, but they've sure kicked butt on the springers this year)who use PURE Anise oil with an obvious high degree of success. Try some of your local smaller pharmacies, that's where I found it. I've used the extract version (Schillings)from the grocery store on my herring brine in the Fall with good success, but recently bought some of the "pure" stuff to try. Haven't had a chance to try it yet though.
Skrimmy, glad to help. I looked around town for pure Anise Oil and couldnt find it so started searching the internet and that was the best deal I could come up with. In a pinch I will use extract but prefer the Pure oil if I can get it.
Be careful about adding scents to your eggs during the curing process unless you know exactly what fishery you are goin got us thme on. IE: you add anise to 6 jars, take two fishing and the fish don't like anise that day, your hosed.. Add it to the indivudal bait when fishing.........