As Cait said, it could be an inner ear infection. It could also be a broken or fractured neck bone. Old fashioned metal wheels are good ("bad?") for this but it could have happened a myriad of other ways. The mouse needs to be seen by a vet immediately or euthanized, either way.Lime Green Mouse said:This can't be anything besides a neurological disorder, could it? Could it be an ear infection or something fixable?
This is unpopular to say, but I will say it anyway: Since your finances are so very limited, and you're potentially starting out with inferior stock, perhaps reconsider breeding mice in the first place. Contrary to popular belief, it is not cheap by any means to properly care for mice, as any trip to the vet or other costly medical ailment will show you!
The only thing that's "cheap" is the mice themselves, so people often get the wrong impression that it must be cheap to care for them. They don't realize that giving adequate care to a $2 mouse can be hundreds of dollars a month, especially if you start out with illness-prone petstore animals!
I don't mean to discourage you (believe it or not, lol), but it needs to be said that giving good care to mice can be quite costly.