What I did was buy the large cheap HEB brand ACV, then one small bottle of Bragg's. Poured the Bragg's evenly to the three containers of HEB ACV and let it sit for a week. When they all had a good amount of "mother", I would start using one, buy another cheap bottle put some into that and just keep it going. I feed down near my "green house" but water up near my house, so I have 1 bottle at each location with 2 getting ready at all times.
Scratch is the easiest to ferment, I use that fermented water over and over, just adding more scratch because I can keep the water over the top of that. However, on my feed, since I don't use the dual bucket method, I can not keep the water over the top of the feed, so I just make 2-3 days worth going in each one but staggered. then when it runs out, I clean the trash cans out real well and get the next batch going. I use more ACV doing it this way, but I don't have to worry so much about botulism (sp?).
after reading some of the fermented feed thread I am thinking I may go with a big trash can.. use 50 pounds of feed in each one and refill when I get to the bottom