These should be a good start:
9mm, 38special/357mag, 40s&w, 45acp for pistol
.223/5.56, .308 for rifle
As far as equipment, Dillon progressive is the way to go. I forget what model # is tops right now but I'm sure somebody will chime in to tell you.
Lee single stage if you wanna sell something lower in price and for beginners.
powder measures, digital scales, bullet trays... the list goes on and on.
Good recommendations. I'll add to the list the Lee Turret Press - great for beginners. In addition you may want to stock the Lee Carbide 4 die sets for the pistol calibers. Lots of reloaders, myself included swear by the Lee Factory crimp die that comes in the set. In addition I'd add 45 Long Colt to the recommended list noted above by robar.
For powders I would recommend carrying Accurate #2,5,7 and 9 along with the Hodgdon and Winchester equivalents for pistol powders.
I used to buy all my reloading supplies at SW Shooters but since they went the way of the dodo I'm stuck with the internet and H&H when I want something quick. Neither is my 1st choice. I really miss SW Shooters.