The S6 is...
a very new tire, and seems to be quite popular at the moment. I haven't found anyone that isn't out of stock on them currently. You likely won't find a "good price" on them for the time being. They're to new and selling to well. You might find a $2 to $3 difference, but they'll be pretty close to msrp, between $48 and $55, depending on size etc.
So keep an eye out, availability is sketchy at present and prices are close to msrp. But it should get better once things calm down a bit.