I don't think this is one of those cases where you tell the OP to go get this and go get that, put it in and you're good to go... Take it to a mechanic, explain what is going on, mention the plastic elbow needing to be replaced, get an honest quote.
If you don't like those numbers they give you, then start rolling up your sleeves and prepare to get dirty and possibly mess it up even more than it already is if you have no mechanical inclination at all.