Leeprecision.com makes a full .45-70 reloading set up (Lee Classic Loader) for 25.95. All you need is a rock, or a branch or some heavy object to use as a hammer. You can make what you need and what the rifles likes rather than having to settle for ammo that is designed for the average rifle.
The Lee Classic Loader is an old design going back to the Civil War era and the design turns out quality, target level ammo for very little money. It doesn’t look like much but it held a world record for the smallest group at 1,000 yards for 7 years in the 1990s. This is what I use exclusively.
I would see if anyone in your area has some handi rifles so you can handle them. The need to handle Black Bear with a light rifle is going to be very difficult to meet and since it might be you life your life on the line, I would not necessarily go with a smaller round.
By the way, the Handi rifles are legendary as reliable, accurate rifles. And the price is right.
I can’t argue about the price. It’s certainly affordable.