Rump, or Bottom Round, is not a very tender piece of meat...as there is very little marbling in the beef cut. Are you looking to make this into a Pot Roast only....or considering it as a roast beef as well? If for the latter, then I would say it's not a good choice unless you have a machine slicer that would enable you to make very thin cuts for sandwich meat......assuming you like your meat cooked less than well done.
I did a recipe which I found on Ezra Pound Cake website for pot roast (ina garten recipe). Yes the price for the rump roast was reasonable. After two hours oven baking 160 degrees, I found the meat very tender and there was a lot of gravy. There was a similar recipe on Saveur for the slow cooker.