Don't care about the cost as I won't be buying it. But some people always will, so complaining about cost is pointless. If it's too expensive for your tastes, don't buy it. Simple...
But (and I haven't tested out the newer versions of this to see if it's been fixed) the problem with the whole system is you have no real idea when you use the buff what extra space you'll have afterwards. This needs to be made clearer - if you're going to invest gems in something, it should be clear what you're getting back in return.