I use a MEC 650 press for loading. As said above, buy a flat of good Winchester 3 inch shells and you will be good for while. I pick up a few new boxes each year to keep some fresh ones in the batch. I get on average 15-20 loads out of them before the plastic splits or the brass cracks. I picked up several thousand wads a few years back and haven't looked lately for local availability, but I see them regularly at many gun shows.
I stick to the 3 inch hulls so I don't have to rest my press and they have much more poop than the shorter ones. Last time I figured it out was about 14 cents per load, but it wouldn't surprise me if its up a few cents now.
Expensive shell to buy, but the cheapest to reload.