I lost my original TI-89 that I came to love in college when I moved from my first engineering job.  I found this one for cheap and was a little skeptical on the quality before I received it, but figured I wouldn't be out much money-wise.  It blew my mind how good a shape this calculator was in when I got it.  The batteries must've been old because they had a leaked a little, but I cleaned it off, put in fresh batteries, and it has been working great ever since. The only thing missing is one of the rubber pieces on the case, but I don't consider it a loss at all.  I'm very happy with this purchase.  This purchase gave me confidence to consider other used purchases.