Use a support ticket to ask when if they know when it will be back in stock. If it's going to be a short time period, I would wait for it. Otherwise I would pick something else and then begin saving the points again.
I agree with mpfm. If I was saving up for something and then bought something else because it was out of stock but then popped up a couple weeks later I'd be pissed haha
I say create a support ticket an find out when it will be back in and save. If your luck is like mine just as soon as you spend it your item would come back in.