I've always been the type to stock up when I got a good deal. Many years ago, someone posted about a deal on Shadetrine algaecide which was simply relabeled Pooltrine 60 for about $5 a quart. I bought all they had. Unfortunately, all they had ran out when I closed my pool last fall.
At the time it was a good deal, because if you shopped around, about the best deal you could find on polyquat 60 was a little less than $10 a quart. Now it's typically more than $20 a quart and there is usually shipping added.
So after searching, the best price I've come across is at Pool Geek. If I buy 12 quarts or more, I get it for $17.37 per quart with free shipping.
Anybody find a better price than that? Even with the sales going on this time of year, I've not had any luck finding a cheaper source.