running wheel?

I been wondering if I should get a running wheel for my breeding mice. Or should I just get them for the soon to pop mothers. Any advice?

i say you might as well get one either way, it'll give them something to do at least

Don't bother with them. They're a pain to clean, and more trouble than their worth. :P
Just give your mice some crumpled up newspaper balls, toilet paper tubes, or small cardboard boxes. They'll have just as much fun, you won't have to clean and re-use them, and they're free! :P