It happened to me many times, there is a quest which need to acquire some ammount of resources and pay (usaually) the same ammount, but you can pay ONLY after acquiring and if I have no room for the resources I have to e.g. sell them or use them for some buff etc. So in the end it cost me double ammount of resources and also some of them are difficult do sell or even get rid off.
I think there should be an option to pay resources first and then wait for acquring the rest.