Why would you still want a gem dispenser? Even if it costs only 225 gems, it will take almost 4 months (most likely longer) for you to get back your purchase price. Look at where BS is heading now. I wouldn't be suprised that they stop giving us weekly updates 4 months later. So you would end up with a bunch of gems but nothing to buy.
My suggestion: if you have 200+ gems at hand, spend it whenever you see something you like. Don't save it for the future because there may not be one.