I bought a Hornady LNL-AP W/case feeder and because of the components I shoot and the equipment I already owned, I had a return of 1.7 years on 9mm vs. buying factory practice ammunition. I already had two other presses, one progressive, one single stage and had all the peripheral equipment to go with them.
It still was 1.7 years to pay for this high production machine over buying factory 9mm.
Yes, I can load my 9mm for $6.00 a box also but if I had to start from scratch and buy everything I have now related to 9mm, my "rate of return" would be much further out then 1.7 years.
It all depends on what press and equipment you buy if you don't have any, how much time you want to invest that you don't get a return on, and most importantly (as so many here have pointed out) how much you are projecting yourself to shoot.
Most of the "cost per round" you see here is only for the components and don't reflect the equipment required to load the ammo.
The last progressive I bought was $700.00 and that took the 1.7 years to pay for with me shooting 6000+ rounds a year of 9mm and already owning all the other things I need to run this press. (powder scales, dies, trimmers (don't apply to 9mm) and so on. I had to apply my .357magnum loads, 41magnum loads, and the other pistol calibers to get the 1.7 year payback because of what I pay for my plated bullets over casting my own lead for everything I load.