I say go for it! I know I would. $50 isn't that much considering how hard it is to get this phone and people are selling them for way more expensive than that.
i don't think it would hurt to check it out. make sure it's in satisfactory condition, pop in your sim card, test that it can make phone calls and get data, and take a picture to make sure the camera works. if it doesn't feel right, walk away from the deal.