We always try to keep the availability information of all our products as up to date as possible. When we indicate that our supplier still has stock, there's a very high probability this is correct as we update this information daily. However, we are not the only ones buying from them as there are many stores worldwide, so there is always a chance that someone else buys the last available copies before we can.
So no, it's never 100% sure, but we will always do our absolute best to obtain whatever you want to buy!