I just bought a 150g bucket of Coralife salt (it’s decent) for $22.39 with free shipping. It gave me a double 35% discount for signing up for auto ship (can cancel later). That might be a better deal.Ok, not the buckets but how about this at Petco?
15lb bags of Instant Ocean are on sale for $11.99, PLUS they currently have a buy 2 get one free offer on the website. That is $23.98 for 45lbs (I believe the buckets are 46lbs) plus $5.99 shipping. Buy 6 packets and get free shipping to save even more.
PLUS, if you haven't used the recurring order promo yet, you can get 35% of your first order and the offers are stackable. I have just ordered 9 packets (equivalent to just short of 3 buckets) and the total, including shipping and taxes, was $56.22, which works out to an equivalent of roughly $19 a bucket
Hopefully I haven't got my maths wrong, as I now have a lot of salt on the way