R you talking Exhaust Manifold

this things are expensive. The original one is made of cast iron. It costs you a few hundred at no surprise. Try to find an after market one. If you can find one made of sheet metal, that is the cheapest. You can not use sheet metal exhaust manifold if you live in CA.
Also, I would suggest you to get it changed at a shop since you are not so clear about I4 engine vs. V6 engine.
Like other people said, the bolts can be rusted and hard to take off. You busted the bult and have it broken inside your engine, it will cost more to fix.