Is there any way you could find out aout her history from the previous owner? Perhaps the store could get in contact with him about it... Personally, in a case like this, I would buy her.

I've always been a softie for rescues. If nothing else, you will have rescued an 'underpriviledged' animal and give her another chance at finding a happy home in which she'll be loved and well cared for.

I say do it.