I was following the EOS sale over the last weeks. I always compared the price from kraken to the EOS sale one and noticed that there is not much difference to be honest. Yes there were a couple of hours at kraken where EOS was trading for $6 but that was just silly.
So basically at this stage I would buy them at kraken since there is not much difference between them but that might change over the coming months. Longer the sale is on better chances to get a bargain