Just recently got into reloading. I shoot a few times a week, but for short durations. My intial investment of $150 has already grown to $250 but is still very close to paying for itself. Once I add a few more items, I plan on getting a progressive press.
I put it off for a long time, saying that I could buy lots of ammo with the initial cost of reloading equipment. Buying a press was one of the best financial decisions I've made; now I can't believe I paid $18 a box for anything! Primers are still hard to find, but I started buying them before I even had a press. My local shop has a 200 per day limit on them, so they have primers in stock more often. I shoot maybe 100 rounds per week and pick up 200 primers per week, so I'm good for now...would like to buy in bulk for savings though.
It's not always a cost savings though, like many have said the more you reload the more you shoot. I have found that I like reloading though, and enjoy it as a restful hobby. Due to practice and tailoring loads I have much better results than with factory ammo, at significantly lower prices.
You can get a basic Lee setup for $120, including dies. You can actually get started for cheaper than that, but the extra $30 or so is worth it to buy the nicer kit instead of adding pieces on later. If you're shooting 9mm ammo costing you $15 per box, and can reload it for $5 a box, your setup will pay for itself by the time you load 600 rounds or so.
The only reason I can see not to is if you have basically unlimited financial resources, access to an endless supply of ammo, you don't enjoy reloading, and you feel your time is best spent doing something else. I'm betting that if all those apply to you, you probably don't enjoy shooting in the first place.
