Ok Midwayusa lists Grizzly .357 maxi ammo 200 grain at $29.99 for a box of 20. That's $1.50 every time you pull the trigger. A random load from my Speer manual using 200 grain bullets shows 15 grains of 2400, and CCI 400 primers for a velocity of aprox. 1,500 fps from a 10" barrel.
A box of 100 jacketed bullets is about $23
primers are about $34 / 1000
powder (2400) is listed as $17.50 / pound
brass (new) $27.50 / 100
That works out to 57 cents per round. If you use free brass (reclaimed from your shooting sessions) the price drops to 30 cents per round. That leaves a dollar to a dollar and twenty seven cents every time you pull the trigger, to buy a press and loading dies. That first 100 rounds will cover a Lee press and a set of Lee Dies. If you shoot 20 or fewer rounds per year factory ammo will work fine for you. If you are like most guys I hang around with, however, 100 rounds per year is a normal year, and a couple years shooting will easily cover the price of getting set up to reload.
Keith