I'll second all the above. Cost savings aren't much. If I can reload .308 for $0.64/round, and southwest ammo can do it for $ 0.74, and I can pick up an extra shift at the ER at when I start in July, then, well, I'm actually paying good money to reload. But, if I'm doing it because I like working with tools and with my hands, for the serenity of mind that comes with doing something monotonous and precise, then it's time well spent. To give the example, I don't keep a reloading press on long island; friends have them if I really need it in a pinch/shtf/whatever. For the 80hrs/week I work as a resident, it's not worth it to me to spend that time, especially when I'm capped at 200yds. I just don't see a sufficient cost difference to invest in my own setup. But, when I travel back to my folks place, me and my dad find it relaxing to sit at the reloading bench with a beer, talk politics, look out the back porch windows, and load .308 and .223 en masse. If I'm doing it for speed, and not for calm, then I can manage about 90sec/round as an average. I'm not trimming case length, de-burring flash holes, etc; I'm depriming FGMM, tumbling, shaking out the media, priming/neck sizing in 1 press, loading powder, and seating bullet. I'm not checking weights or capacity. I'm not checking concentricity. I'm not doing a lot of the more time consuming practices. I am individually weighing each powder charge.
If you want the fast answer, 100 rounds of FGMM brass will take you about 150-180 minutes of actual work. Your cost savings vs. new ammo at 30$ for 20rds, vs having Southwest Ammo load for you at 74cents/rd will be 150$ new, 85$ for SWA [gotta ship them the brass and wait, er, 4 months, in my case] and 65$ for me to do it myself. If you're gainfully employed with spare income, don't mind waiting forever, and don't enjoy doing the monotonous thing, and don't feel like shelling out a few hundred bucks for a press, then just buy your ammo in bulk, shoot the hell out of it, and send SWA 500 rounds of brass at a time. I tend to keep a few orders at some stage in their process, and thus am never short.