I tend to buy the cheapest available from established brands like Winchester, Remington, UMC, or Federal. If it's one of the steel-cased import brands like Wolf, I'll pass unless the price difference is considerable (25% or more), as I don't like the messy residue they leave behind in the chamber.
My one exception is .22 ammo. If I am plinking, I go for the cheapest bulk. If I am doing bullseye shooting, I will spend more for good standard-velocity target ammo (specifically, Remington when I can find it).
For the cheap stuff, if you can come close to WM prices on Winchester white box and that level of stuff, then with a little word of mouth I'd bet you get lots of people who will buy from you instead of feeding the China machine. I would! Same with bulk .22 ammo. People are funny though... they'll pay $12 to get into a gun show and buy one box of ammo at what is usually more than retail price and think they are getting a deal.
Around deer season, you might want to think about making sure you have some premium ammo in the most popular deer calibers. If you track all of the hunting seasons, you should be able to stock for each season's most popular ammo(s) and be able to sell well. Ie. Magnum 12Ga during turkey, Dove loads around labor day, etc...
I think some consideration on advertising will go a long ways too... word of mouth gets around quickly, but even doing some things like donating for a giveaway at the Red Castle meeting and putting your name in their bulletin as well as the other gun clubs will help speed the process without much cash expended.
I'm hoping you are very successful and will help any way I can.
Like everyone else, I'm looking to save some scratch as much as possible.
I usually get Federal ball ammo from Walmart in all calibers, but the only thing I don't like is they only have 115 grain 9mm.
I would like to find a good deal on some 147 grain 9mm, so if you start selling that then I might just have to buy from you and help out a fellow OSA'er.
I reload everything but my duty ammo. That I will buy new. Usually Gold Dot but I have bought WWB hollow points. I will also buy Federal XM193 or Winchester Q3131 when I can find it for a good price. If you carry a good selection of reloading supplies I bet you will do a brisk business.