Talk to the manager and see if he will either reduce the price drastically or even give it to you. It really shouldn't be out on the floor, or so I've been told by folks at my Petco and PetSmart. Oh, I don't believe them but that's what they say!
I would try to avoid paying full price, explain that it is underweight (and, obviously, tail-less) and isn't "sell-able" in it's current condition. Can't hurt to try.
In general, I think you should not buy it for the whole 'it only feeds the cycle' of the big pet store debate. If it were me though, who knows, I might just ignore my own advice and take the little fella home!![]()