There is a reptile show this weekend - I have a bunch of items I plan to pick up while I'm there.

I believe the previous owner was feeding mice. Should I be worried about buying bulk rats? I don't want to get a bunch of rats and then learn the snakes would much prefer to stick with mice.

Also - It seems like I need rat weanlings or XL mice. Mice seem to be cheaper. Can't find an good explanation for why this is the case beyond the convenience of size. Can someone explain which would be preferred and confirm the sizes I mentioned are correct for my BPs?