You can get in to casting for several reasons. It is just like reloading, you can play around with different options to really end up with some accurate ammo. Then you can come at it from the cost savings point. If this is the angle, you need to have an idea of how many rounds you fire in a period of time. I thought I would shoot much more than I do but I am sure I will shoot more when I fully retire which is what I keep telling myself. Thirdly are those and I am one, who does it to produce something with my hands. I would do it even if I didn't save money, there is just something about having thousands of rounds sitting there reloaded in plastic cases ready to go and more thousands sitting in coffee cans just ready for the bench time.
In my early years I worked in auto collision and loved fixing things. Then I got into education and administration and I found out I needed to keep my hands busy. Reloading and casting fit that bill and it is almost as much fun to cast and reload as it is to shoot.
As has been said here, finding the lead is the challenge. I belong to a range and we can bring home what we want, at least for now. I then have found some good buys on wheel weights and some free. Just start asking around, you will be surprised how much is out there just for the asking. I think what every shooter should do, and I am working with a friend to do, is build a bullet trap. It is ridiculous to send countless lead bullets down range into the ground. There is always some that will be lost but we recycle most everything, why not our bullets? There are some crude but effective bullet traps on youtube. Get your buddies to come shoot on your trap and harvest their lead. You will have more than you can use and save the environment (note I am not a tree hugger).
Don't get in a hurry to find equipment. it is out there and if you are selective you will find it. 9mm is not the best round to start with. Go with a 158 grain SWC and get good at that first. I pour 9mm, 38/357, 40 S&W and 45. I work on loads for long time to get them right so I am slow. Right now I have the 38 where I want it, real close on the 45 and ready to start full bore on the other two specific to my handguns.
I am looking forward to working with my new smelting set up this fall when things cool down. Then I want to build some wooden boxes to store the ingots in. I go to
http://castboolits.gunloads.com/ every day to learn something. Good people there. Have fun with it.