I wouldn't pay a hundred, I'd offer $50, ask them to throw the bent housing for free or tell them you'd bring it back after you got the gears out. Myself, I wouldn't think twice about running used gears as long as they don't have heat or physical damage. I like saving money however I can.
I just came back from the JY where I got the rear axle . They are firm on their prices . The other axle is at another yard , I'd like to open it up before I bought it to make sure they are not damaged . Maybe he'll wheel and deal ...