We use Bromar lick feeders from Bromar Engineering at Grenfell, NSW.
We have found these to be good because you can run grain or pellets through them. You can also fine tune it to make sure the sheep are getting the exact amount of feed that you want them to.
You need about one feeder to 100 sheep.
Bromar Engineering also have an option to buy their seconds for a cheaper price. These feeders are still structurally sound, but have cosmetic faults.
I hope this is useful!