I reload 9mm, 38spl, 40S&W and 45 ACP.
Cost saving varies with the least benefit on the 9mm. It costs me about 15c per 9mm with free brass vs $280-300 per 1000 from the store. I use a Dillon 550 and produce about 350 rounds per hour.
In pure cost terms I don't think it is worth setting up to reload 9mm only. The setup cost is about $1,500 for my type of rig. That is a lot of 9mm cartridges to break even, over 10,000 rounds. You need a dedicated place to reload and appropriate storage for the powder, primers and loaded cartridges. All need to be locked in separate containers etc etc. So you need a significant amount of space which needs to be kept free of spilt powder etc for safety reasons. In addition there are significant safety issues with reloads. It is very easy to double charge some pistol cartridge cases, although this is tough with the 9mm due to its small size. Your gun may survive a double charge but it may not and you can badly get hurt by this. I have seen the result of a gun blow up. Not pretty. So care and attention to detail is vital. Personally I have switched to bulky powders to make the double charge much more obvious. A lot of modern powders are very efficient so the case can hold up to a triple charge. Case in point, 38spl and 357 mag (pun also intended).
The big advantage with reloading is that you can optimize the cartridge for the gun. A second advantage is that if you start reloading other cartridges the cost of setup is much smaller at $200 or so per cartridge so you get much better bang (pun intended) for the buck. I save about 20-25c a round on the 38, 40 and 45. That can mount up quickly.
Personally I enjoy developing a cartridge and then the reloading itself. I love making things so for me reloading is fun in its own right. Lots of others find it a chore. I am now upgrading my reloads for improved accuracy which you can do relatively economically with reloading it just takes more time and care rather than more cost.
In summary lots of things to learn and some inherant risk and you will spend the same money overall, you will just shoot more.