Jumping in late on this one, but seeing as nobody suggested going for the grain mill I figured I would add my 2 cents. There is no doubt that fermentation temperature control would do more for the quality of your beer, but a mill is one of the few pieces of equipment that will pay for itself and then allow you to save enough to buy that fermentation chamber.
I pay about $0.77/lb for bulk base grain, while the LHBS charges $1.60/lb for the same grain by the pound. For every 10 pounds of grain I use, I save over $8. Over the last decade my mill has paid for itself many times over.
As an added bonus, if you ever get into a bind and need to sell your mill, used mills go for almost as much as new ones so it is really a no-brainer!