Like anything else, the sky is the limit. You can start off with a single stage pres and get completely set up to load one caliber for probably in the $200 to $250 range. Loading single stage will allow you to load maybe 100 rounds per hour. From there, you get into turret presses and progressives. I have two progressives and can load ~1000 rounds per hour or more. But the presses are a lot more expensive, too. You can get into a good progressive for ~$350, but you still need all the stuff that goes with it, powder scale, calipers, etc, etc, etc. With the progressive, you can probably get started for $500 to $600.
Where you will find your biggest savings in reloading is buying components in bulk. When I buy bullets, I buy anywhere form 5000 to 20K at a time. Same with primers and powder. A 1 pound jug of powder will run you ~$20. Buy 8# jugs and you can get them for less than $100 per jug, and the more you buy, the cheaper it gets.
Here is an example of what I use in my 40SW loads. Hard cast bullets at $40/1000. Hodgdon Titegroup powder, 8# for $96 (14,000 loads for 8# of powder. Primers in bulk for $19/1K.
Bullet, 4 cents, primer 1.9 cents, powder .6 cents. Total 6.5 cents per round, $6.50/100 rounds and $65 per 1000 rounds.
If you go down to your local gun shop and buy the components, here's how it will break down. 1# powder $20, 100 primers $2.50, 100 bullets $15. Bullet 15 cents, powder 1.1 cents and primer 2.5 cents. $18.60 per 100.
In the end, you'll have to be the one to decide if it is worth it to you to reload.
