KO KO

So I think I can get a whole rear end because my friend's dad is telling me that it would be cheaper to replace the rear end than just the seals because he thinks replacing a lot of the brake stuff will end up costing too much.

I really wanted to try to change the seals, but since I really don't know enough to do it myself and really don't want to screw up, what should I know about replacing the rear end and finding a new one?