You'll find prices in the catalog which is now hosted on this site at the beginning of my forum. But while you are reading. 2 cavity are $125, and 4 cavity are $175.
Maximum nose length for the Blackhawks is .45, for Redhawks, .5, but these lengths are only available in the LFN profile, in 280 gr and heavier.
The WFN should not have a nose length longer than .4 for any gun, and the WFN is the bullet I reccomend for you. Since your main concern is bear protection, get a gas checked design and drive it at 1450 fps maximum, for fastest kill speed with poor hits and in tough going. You can get that speed easily with a plainbase if your barrel is a proven performer with plainbase, which means it has had a lot jacketed through it with very frequent cleaning, or has been lapped.
Diameter needs to be what will slip snugly through your particular guns cylinder throats. They are all individuals in respect to internal dimensions.