Transferring 9000 Alien Materials from one base to another isn't fun. I think the simplest, and most user friendly, way to speed up buying / selling / transferring large numbers of an item would be to adjust the code for the spin control to use an increasing increment.
e.g. Click, and hold, on 'up' and you get +1 each time the counter clicks up for the first 10 or so, then +5 each for the next lot, then +10 each for the next bunch, then +50 etc.
Well, exact values can obviously be tweaked by the programmers to whatever looks nice, but that's the basic idea.