Well it's limited, as long as they don't have an other sale
Since I joined 2 months ago, they had 3 "sales" in a row.
I asked them if the price would come back later, because I needed to wait 2 weeks after the current sale. They told me they can't guarantee it will still be active, but if he would have to bet, he told me yes.
So the sale "should" be here when you will sign up.